Ubisoft's terrific Assassin's Creed II launched just yesterday and it really is something extraordinary - a game so impressive it's more than worthy of some special treatment at the hands of Digital Foundry. As discussed in this week's Face-Off, one of the key improvements made to the original Assassin's Creed engine was the addition of a full day/night cycle, and we were eager to test that implementation.

There's no better way to do this than by undertaking one of our painstaking, time-consuming, but really very cool time-lapse videos. Just a few special ingredients are required to put one of these together: the ability to go anywhere within the virtual world, a first-person view with no intrusive HUD, and finally, phenomenal amounts of patience. In truth, the biggest challenge with this one was keeping Ezio as still as possible (you might notice the odd bit of "wobble" on close objects where this wasn't possible).

What we have is a collection of 31 time-lapse locations, covering 10 days of in-game time across four cities, from the rustic charms of Florence through to the sheer beauty of Renaissance Venice. It's Assassin's Creed II as you've never seen it before and certainly won't see it elsewhere. In addition to the streaming options, there's a download version on the EGTV clickthrough, along with this mega-bandwidth version designed for playback on Xbox 360 and PS3.

10 days of in-game time from four major cities featured in Assassin's Creed II - presented via the beauty of time-lapse video. Music by ACII maestro Jesper Kyd.View this video in HD

It's intriguing to compare the virtual world Ubisoft Montreal has created with Rockstar North's incredible Liberty City, as seen in GTAIV. Both do a superb job in providing a fully immersive gameplay environment, but the two approaches - time-of-day lighting and shadowing aside - are very, very different. Rockstar has attempted a fully featured approximation of city life: a bewilderingly vast array of different AI behaviours for the characters, a full weather system, and of course implementation not just of NPCs, but also a complete range of vehicles too.

Assassin's Creed II seems to follow a different philosophy - the creation of environments that look incredible "in the moment", but don't really aspire to any lofty pretensions of creating a full-on simulation of life in 15th century Italy. Aside from their penchant to occasionally delve into your money pouch or engage you in rooftop chases, AI behaviour of the citizenry is unremarkably routine (those poor courtesans don't seem to get much "traffic"). Horses and vehicles aren't allowed within city limits. This "almost but not quite" approach also applies to the renderer too. The time-of-day lighting is quite superb, but the sky itself looks to be a simple 2D bitmap wrapped dome-like around the environment with a layer of atmospherics overlaid on top. It's an example of how compromise only really manifests when the engine is put through extraordinary scrutiny (as time-lapse video is wont to do). In-game it just works and looks great.

The core tech within Assassin's Creed II is very similar to that seen in the first game, which at the same time proves just how far ahead of the curve Ubisoft Montreal was in 2007, but makes the slightly dodgy performance stand out somewhat in the present day.

However, aside from the implementation of the day/night cycle, there have been other improvements too. The developers have rarely discussed the new "Scimitar" engine for ACII with the press, but mooted additions have included improved lighting and reflections (essential for the spectacular Venice cityscape, obviously), while the vegetation generation system pioneered in Far Cry 2 also gets ported over for inclusion within the revised tech. Ubisoft Montreal has also made headway in improving the level of detail (LOD) levels with new streaming tech that resolves higher-quality art further away in the distance.

However, the limitations of the original AC1 tech do manifest, most notably in the cascading shadowmaps within the game. Detail level of shadowing changes dramatically at set points ahead of Ezio, most noticeable in the video at around the 00:57 mark, where shadowing on the central tree is divided half and half between higher and lower resolution renderings. Noticeable geometry popping (scenery appearing from nowhere) is also another issue that is reminiscent of performance in the first Assassin's Creed and still manifests even after hard-drive installation.

Ubisoft's technical achievement here is still sizeable, but if you're thinking that the scale and diversity of this open world causes issues in terms of storage space available on Xbox 360, think again. Assassin's Creed does indeed effectively max out the available DVD space, but whereas some publishers release different game variations with support for individual languages, ACII features full audio support for English, French, German and Italian on the same disc. Each of those sound packs takes up around 200MB of space on the DVD, and over and above that, there's also another 100MB spent on a trailer for the forthcoming Ubi/James Cameron Avatar game. It's also interesting to note that the PS3 version of the game occupies pretty much the same area too.

In one sense it highlights the excellent levels of compression that Ubisoft Montreal achieved in ACII, but on the other, it does rankle slightly that one of the annoyances of the original game - repetitious dialogue from the citizenry - once again rears its ugly head in the sequel. It's an element that we would really like to see improved in the sequel.

Ubisoft is on the record as saying that Assassin's Creed will be a trilogy of games, so it will be interesting to see where the developer is heading for the next title, and whether the existing engine will stand the test of time for a third outing - presumably in 2011, when the current HD consoles will be well into their twilight years. The sheer volume of content in ACII, and the fact that the game itself is simply so utterly cool more than mitigates any of the technical shortcomings in the here-and-now. But come AC3, we can't help but wish for the complete package.

So, Call of Duty: Modern Warfare Reflex on the Wii. The basic idea of bringing one of the most advanced HD console shooters to the Nintendo platform sounds ludicrous, but Activision in concert with its Treyarch development studio has only gone ahead and done it, and the result is pleasantly surprising. Wii owners get a surprisingly fully-featured rendition, which even includes the lion's share of the online gameplay as well as the customary Wiimote-powered "waggle" controls that you won't have experienced in the initial release.

The notion of porting Modern Warfare to the Wii isn't so whacked out or as ker-azy as you might initially think for a number of reasons. The first Modern Warfare's core engine still has a fair amount of DNA left over from the Quake tech upon which the Call of Duty franchise itself was born. The basic setup of the levels in Modern Warfare offers little that any last-generation shooter couldn't cope with, and this is born out by the quality of the conversion in the Wii game.

Content-wise, it's pretty much all there. Compare and contrast with the new stages in Modern Warfare 2, streaming and decompressing on the fly from the disc - providing a vastness of scale never seen in the series before, and almost impossible to replicate on Wii without some serious re-engineering.

More than that, in some development circles, there is the school of thought that porting over your Xbox 360 game to the Wii is actually easier than it is in developing it for the PS3 (swap over the 360/PS3 roles if you like, the point remains the same). Essentially, in a market that demands platform parity in its HD console releases, the amount of effort required to achieve this is pretty exhaustive bearing in mind how different the base architecture is. In porting over to the Wii, developers face no such pressure - they have carte blanche to cut down and remove whatever they like, just so long as the final result looks okay and is playable.

Modern Warfare on the Wii. Graphically rather functional, but the last-gen elements of the core engine tech help make the transition to Wii easier to swallow.View this video on EGTV

That's exactly what Treyarch has done with Modern Warfare. Texture detail and geometry levels are savagely hacked down, lighting effects and shadowing are brutally pared back, frame-rate is cut from 60FPS down to the more manageable 30FPS (and even then it has trouble sustaining it in some of the more sustained firefights). The whole lighting model has been adjusted to such a degree that the night-vision section in The Bog is entirely superfluous - despite the game nagging you to don the goggles, the section remains so bright you don't actually need to.

Graphically, Reflex is functional, looking pretty much as you'd imagine a PS2 version to look if handled by a reasonably competent developer, but put it this way - Criterion's Black this ain't. However, stick the Wii game into a side-by-side comparison with the PS3 version and you can see that despite the vast array of cutbacks and compromises, it does a good enough job of capturing the look of the original.

A standard def head-to-head between the Wii and PS3 versions of Modern Warfare. The Wii game is serviceable enough but when Criterion's Black still looks so much better, it's clear that no technological barriers are being pushed back on the Nintendo console.View this video on EGTV

Reflex follows a very different gameplay strategy than its HD siblings. Infinity Ward prides itself on ultra-low latency controller feedback and targets 60FPS gameplay to achieve that. In the drop down to 30FPS, that feedback has been compromised, but then again, the IW control system itself is history.

In swapping out the joypad for the remote (no MotionPlus support, sorry), the lack of 60FPS doesn't really matter bearing in mind the additional "latency" of dropping the controller-based system for the use of the remote instead. Moving your arm about incurs much more "lag" than using your fingers and thumbs on the tried-and-tested joypad - the trade-off being that pointing with the Wiimote should feel more instinctual, and you should be able to target the enemy more quickly.

The Wii's waggle system operates on a similar basis to the scheme found in The Conduit and there are moments where Reflex feels great. Running across the battlefield, firing from hip, works beautifully in that you can spray fire anywhere you want, without it affecting the direction you're running in - you can't do that so easily on the HD console versions. Similarly, the process of using ironsights, the sniper scope or just lobbing a grenade is transformed completely. If the overall "aim" in using these modes is to get more precision and control, the effect is boosted immeasurably through the use of the Wii remote's infra-red pointer.

However, over and above these aspects, the awkward button placement on the controller makes things difficult for anything other than running and gunning and it's here that the control system is left wanting. Lobbing flashbangs and grenades with the plus and minus buttons involves a clumsy rearrangement of your fingers on the remote - chucking back thrown grenades is particularly time-consuming and unwieldy. Attaching the knife to the down button on the d-pad also kills off the whole notion of having an instant form of close-range kill due to the time it takes to move your fingers into position. Over and above that, there is still the notion that simulating head movement by pointing the view weapon to the far left or far right of the screen feels rather unnatural.

That said, there is something here that - when it works - feels worthwhile, and it makes you wonder just what sort of implementation we could see with the Sony motion controller. If the system's mooted PlayStation Eye head-tracking tech (coming to GT5) works well with minimal latency, this could solve the view weapon issue. That, combined with the extra precision from the Sony controller, could make all the difference. A patched up, motion-controlled Modern Warfare on PS3? That's something I'd love to see.

Look out for our review of Call of Duty: Modern Warfare Reflex, with more on the online modes in particular, soon.

We've been planning to put this together for ages, but the recent release of Grand Theft Auto IV: Episodes from Liberty City (reviewed today) proved to be as good an excuse as any to finally put the effort in - not just because the additional content is so cool, but also to pay tribute to what remains the finest, most expertly realised open-world environment ever to hit consoles.

Just sitting back and watching the world go by in GTAIV is an experience in itself, and the range of behaviours attributed to the gameworld's pedestrians is absolutely phenomenal. They drink coffee on the way to work, they sit and read on the benches, they warm up before going jogging, they put their brollies or run for cover when the rain comes, they get immensely annoyed if a car runs into them.

Some of them smoke, some of them don't... They'll even pick fights with one another on the odd occasion. Combine this with the realistic movement of each and every vehicle, along with the uncanny lighting system and the superb realisation of multiple weather types and you can't help but appreciate the sheer technical accomplishment.

The player's focus is of course on the game itself, and the cityscape that Rockstar North has created is taken somewhat for granted bearing in mind just how far ahead of the competition this technology is. Creating and coding the make-up of Liberty City must have been a mammoth undertaking, but in the midst of the involving gameplay it's just background detail as Niko's story unfolds - or Johnny Klebitz's, or Luis Lopez'.

The PS3 version of GTAIV was used for this presentation for a couple of reasons: firstly, we had a save-game with the camera-phone! Secondly, the lower resolution and omission of odd texture-dithering compared to the Xbox 360 game helps video compression immensely. Be sure to check out the HD version for all the intricate details.View this video in HD

There are complaints that the game feels laggy and that the frame-rate is somewhat variable and often disappointing, and it's difficult to argue with that, especially when other open-world games sustain their frame-rates more convincingly. However, it's important to remember that in addition to everything we've just described, Liberty City is a creation unlike any other.

Games like Prototype or Crackdown can stream and decompress data relatively easily in comparison thanks to the multitude of repeated graphical assets, shared textures and more basic geometry. Not only that, but the developers can shape the environment as they please to match the limits of their technology. GTAIV on the other hand is attempting a full-on recreation of New York City, with all the challenges that represents.

Speaking of challenges, putting this video presentation together wasn't exactly a walk in the park. First of all, we needed a technique to sustain a first-person viewpoint without the game shifting into spectator mode. This was solved by using the camera-phone you get later on in the story. Next up, the capturing. GTAIV's day-night cycle lasts for about 50 minutes of real time and we captured around 45 different clips at one frame-per-second over the course of 10 days, not all of which made the cut.

While our previous time-lapse videos have simply faded between day-night cycles, for this one we went a little further. Thanks to the on-screen timer on Niko's mobile, we were able to edit together 15 days of game time - complete and unabridged - encompassing 35 different locations from Liberty City.

It's our tribute to a superb technical achievement that no other open-world game has yet to match, and we can but wonder what the team at Rockstar has planned for the inevitable next GTA offering. With the technology in the bag and still essentially unrivalled, will the developers shift the focus to content creation? Or can we expect an even more advanced version of this astonishing engine?

At around 2.6GB in size, the God of War III E3 demo is one of the meatiest sampler downloads we've yet experienced, but the lengthy wait is worth it bearing in mind the length and breadth of the content on offer. Indeed, there's so much to show that we've cut the video analysis into two parts with only minor edits.

The first effectively covers what was shown in the Sony press conference at E3, the second shows what comes afterwards, and it's here that the demo really comes into its own - becoming that much more of a technical showcase. If you've already eagerly consumed the E3 press materials, skipping ahead to the second vid is probably worthwile.

This video essentially replicates the God of War III playthrough as seen in Sony's E3 conference. Skip ahead if you want to see new stuff, hit the play button to check out the frame-rate analysis.View this video in HD

So, part one then. Our initial technical analysis of the E3 demo remains relevant (it is the same code after all), but what is noteworthy is just how clean God of War III is. It's not really so self-evident on compressed internet video assets.

The texture work is of an outstanding quality throughout, special effects are used in a subtle and reserved manner, lighting is exemplary. The code appears to be using 2x multisamping anti-aliasing, but similar to Killzone 2, the choice of colour palette helps in adding to the edge-smoothing effect.

The second part of the E3 demo playthrough. This is where things begin to get seriously impressive. March 2010 can't come quick enough.View this video in HD

Into part two and the Sony Santa Monica studio's range of effects comes to the fore a touch more prominently. The per-pixel lighting in combination with the high-quality texture work produces some uncanny effects (for example, on the marble). The depth-of-field effect isn't "in your face", it just works and looks superb. The texture filtering employed is of an excellent quality. The only downers are a few low-poly edges and the reduced alpha buffers, but the impact on overall image quality isn't really a problem at all.

So, the frame-rate. Yes, it's E3 code. Yes, there's obviously a better-than-usual chance that the final code will improve over what we see in the demo. However, the performance level in the sampler is intriguing. This rendition of God of War III is v-synced (so no tearing), and based on our playthrough across the two videos, we have an average of 36.81FPS, a low of 24FPS and a high of 56FPS.

Average frame rates aren't usually that much of a useful stat, but here it's a pretty decent indication of overall performance throughout - which is curious. Locking the game at 30FPS would have produced a more visually consistent look, as well as a more predictable, "reliable" feel from the controls - plus less judder on-screen in panning shots and the like.

Overall though, small quibbles aside, this demo is great stuff, and the timing of its release just weeks before the US demo is released as part of the God of War Collection is curious. Will this self-same E3 demo be the same sampler included as a PSN redeem code within the package? Has Europe actually had the "exclusive" here?

Alongside the new Assassin's Creed and Modern Warfare sequels, Valve's Left 4 Dead 2 must surely rank as one of the most highly anticipated games of the year for Xbox 360 users. Currently only available as a bonus to US customers who pre-ordered the game, we've managed to procure the Xbox 360 demo and subjected it to the usual battery of performance tests. This is the first time the Digital Foundry channel has seen the game running, and overall impressions are very positive indeed.

The demo itself is a decently-sized sampling of what is to come. Weighing in at a hefty 1.6GB, the download offers up two levels of The Parish to work through along with online and single-player gameplay. Similar to the first game, the CPU takes control of your three companions in the absence of any human companions. You get to sample a range of firearms, incendiaries like Molotov cocktails and pipebombs, plus the much-vaunted melee weapons. Realistically there's between 20 to 30 minutes play-time, which we've edited down a bit for this six minutes of frame-rate analysis.

Frame-rate analysis of the Xbox 360 demo of Left 4 Dead 2. By and large, the performance level is a match for the first game.View this video in HD

From a technical perspective, frame-rate is essentially fairly solid (30FPS with a few caveats), and, similar to previous games running on the Source engine, we're looking at a v-synced 720p with no anti-aliasing. To smooth off edges a touch, a subtle blur filter has been added. These post-processing effects rarely look that great but here it works in concert with a well-implemented camera motion blur and isn't so distracting. On the plus side, texture filtering is a decent combination of trilinear with a good level of anisotropic filtering.

Where performance is impacted, it looks as though it's down to fill-rate. The biggest dips in the frame-rate graph are where many transparency effects are in play. While the Source engine's setup is seemingly designed for maximum fill-rate, the use of smoke and fog needs to be deployed carefully - geometry that clips through the transparency essentially ruins the effect of it, so the engine continually runs checks to make sure it never happens.

It also looks as though some alpha effects are generated at lower resolutions before being scaled up, most noticeable on the fulsome flame effects seen in the demo (and captured in the video thumbnail above). It's a common technique most often deployed in PS3 titles where GPU bandwidth is at a premium, but it's a good trick that can be used on any platform and it's rare that the user picks up on it.

Overall then, few surprises here: the Source engine on 360 looks to be more than up to the task of powering the sequel. If you fancy a bit of additional information on how Valve transitioned from PC to cross-format development, this GDC 2008 presentation is absolutely fascinating, and worth a look not just for the valuable info, but also for its strategic use of oddly appropriate comedy photography.

News this morning suggests Microsoft CEO Steve Ballmer has done it again, pre-empting official announcements by confirming to Gizmodo that the company is planning a Blu-ray expansion drive for the Xbox 360.

When asked if forthcoming 360s will get an internal Blu-ray drive, he replied: "Well I don't know if we need to put Blu-ray in there - you'll be able to get Blu-ray drives, can get Blu-ray drives as accessories."

It looks self-explanatory out of context, but then context is king, and if you watch the original clip it's easy to reach the conclusion that he was talking about buying yourself a separate player for the lounge if you fancy a Blu-ray player, and simply used the magic word "accessories" by accident. Especially as he then talks about video-on-demand being the future in the next sentence.

That said, there's no technical reason it couldn't happen. Assuming an external drive similar to the ill-fated HD-DVD add-on, the technical challenges of bringing Blu-ray to the Xbox 360 are significant, but most of the legwork has been done already. The HD-DVD codebase within the 360's dashboard features support for the same MPEG2, h264 and VC-1 codecs found in the Blu-ray spec.

The only question mark concerns the throughput levels the code is capable of: HD-DVD handled 30Mbps max, while Blu-ray ups the ante to 50Mbps. At the time of the HD-DVD add-on's launch, Microsoft talked about how a combination of both CPU and GPU power was required to handle the decoding. Assuming there's no overhead in the code, it could require significant re-engineering to get it up to BD specs.

Even then, Microsoft would be in the unenviable position of having to charge a premium for a BD playback solution fundamentally inferior to PlayStation 3 performance, most notably due to the limited surround sound options in the lower-spec HDMI 1.2 controller found in the Xbox 360.

Over and above that, Microsoft's strategy thus far has been to say that gamers don't need Blu-ray, and any kind of expansion device would suddenly be suggesting the opposite. Far from offering more value to the Xbox 360, it would immediately make the keenly priced all-in-one PS3 Slim far more of an attractive proposition. Validating Sony's decisions isn't Microsoft's style.

As for games arriving on Blu-ray for Xbox 360: forget it. Some figures bandied about at the time put the penetration of the HD-DVD add-on at a mere three per cent. A BD device would probably be more popular, but the take-up would still be far too low to risk muddying the waters with games available on multiple disc-based SKUs.

In a sense, the Xbox 360's reliance on DVD has defined the storage threshold for this generation. The vast majority of its first-party titles use just the one disc. Third-party cross-platform titles are, with the odd exception, invariably targeted towards the 6.8GB storage limit imposed by the Xbox 360 DVD, to the point where even the PS3 versions are much the same size. The success of the Microsoft console has defined the size of almost all cross-platform games this generation, effectively making the 25GB and 50GB storage limits of Blu-ray superfluous.

In terms of HD movies, Microsoft probably reckons its download-only strategy stands just as much of a chance of success as Blu-ray over the longer term as broadband streaming speeds increase. Its service is also inherently more suitable for the Xbox platform: it's immediate, it's available to all Xbox 360 owners out of the box, it adds value to Xbox Live, and, crucially, Microsoft will make more money from it. Releasing a BD peripheral gives the firm no recurring revenue stream and effectively share-steals from its own services.

Moving into the next generation, all bets are off. The next Xbox will require a higher level of storage and by the time that comes about, a Blu-ray drive will be the cheapest way to deliver that. In the here and now, any kind of move into the BD market would be too little, too late. And besides, Xbox 360 seems to be doing well enough without it.

Naughty Dog's Uncharted 2: Among Thieves is the game that just keeps on giving. In addition to the gameplay, there's a wealth of bonus material on the disc that is well worth a look. Amongst the various goodies are eight behind-the-scenes mini-documentaries concentrating on the developers and their work. The one we enjoyed the most is entitled "Mastering the Cell", an intriguing glimpse into the ways and means in which Naughty Dog has created what must surely be this generation's defining technical achievement.

The documentary is interesting in a number of regards, not least in that it appears that one of the core philosophies behind Naughty Dog's rendering tech is to offload as many tasks as possible from the GPU and stack them up on the SPU satellite processors of the Cell chip. In the case of Uncharted 2, post-processing techniques such as the game's phenomenal depth-of-field effect (pretty much the best seen on console to date) are hived off to the SPUs. It's an intriguing way of using resources. Presumably the GPU would be able to carry out the same task a lot faster, but if the RSX is otherwise engaged in a computationally more expensive task, it just makes more sense to use the SPUs to do the same job.

It's a little frustrating to get such a short and often obscured glimpse of the performance tools in action, but at at around 23 seconds into the video, you should be able to discern on-screen that five SPUs are being maxed out: an impressive feat of parallelisation.

Nope, the game hasn't crashed! Those differently-coloured bars on-screen represent usage of different aspects of the PS3 hardware. Presumably the bars are colour-coded according to the task being performed at that point.View this video in HD

Other bite-sized snippets of information we learn from this video: firstly, the game appears to be achieving throughputs of up to 1.2 million triangles per frame, effectively 40 million per second. Secondly, some of the debug info shown on-screen is literally quite illuminating - the cascaded shadowmap and translucency lighting elements indicate that transparent alpha effects, such as smoke and atmospheric haze, can be affected by the current lighting scheme.

Also worthy of comment as something that's not immediately apparent to the eye, but technically very clever, is the concept of procedural animation, or blended motion. Drake's movement flows more smoothly due to the fact that the game takes its predefined animations and uses the SPUs to figure out intermediate motion to easily move from one to the other without having to wait for a particular animation to complete - this means that the response from Drake to controller commands is that much faster.

The net result is that Drake moves more realistically, and the animators don't need to predetermine every single move possible. What we'd really like to see is this kind of technology moved on to the next level in order to bring some level of innovation to the moribund 3D fighting genre. [Tsk, you and your moribund 3D fighting genre. - Ed]

Returning to the here and now, taking a look at this video, particularly after playing through the Uncharted 2 single-player mode, really puts into perspective its landmark technical achievements.

CryTek has completed development of its new CryEngine 3 middleware and released a new trailer demonstrating its vision for the engine's next-generation capabilities, along with new footage highlighting performance on PlayStation 3 and Xbox 360.

From what we can see, the "Next Gen" elements of the trailer appear to be about the scalability of the new engine and are most probably derived from the technology running on a supremely powerful PC.

The forest scene, for example, is hugely oversampled, but the lighting quality is absolutely phenomenal. The later scenes retain the high quality and showcase high resolution shadow-mapping and absolutely no "pop-up" whatsoever.

After concentrating on console performance in its CryEngine 3 presentations, elements of this trailer come across almost like a love letter to CryTek's dedicated PC fanbase, who've been left to wonder exactly what visual goodies the new engine will bring to their hardware in the future.

CryTek's new video showcase reveals how the engine can scale into the next generation while still supporting PS3 and Xbox 360View this video in HD

The PlayStation 3 and Xbox 360 elements of the trailer are new material based on the assets seen in CryTek's previous GDC showcase. There are no direct shot-for-shot comparisons between the two consoles, but it is clear that there are differences between the two implementations, with the lighting model appearing to be different between the two consoles.

Overall performance seems to be close to the firm's initial GDC video, based on shots taken from the same areas. For example, during the Xbox 360 procedural destruction and physics section, we see that the frame-rate hovers around 20FPS, just as it did in CryTek's previous materials. Both versions of the engine appear to be running at native 720p with no anti-aliasing.

One thing that does look different is the implementation of v-sync. In the GDC trailer it appeared that the PS3 version was triple-buffered with v-sync, while the Xbox 360 engine had some screen-tearing. In this new video, v-sync is clearly disengaged on the PS3 "Rich Interiors" clip. All of this is important as, by CryTek's admission, the engine is now complete. This is the tech that will be powering 2010's Crysis 2, coming to both PC and console.

There's much to be excited about with CryEngine 3, whether you're a developer or a gamer. Unreal Engine 3 technology has dominated the current generation of gaming, particularly in the first- and third-person shooting genres, and this is something new and compelling that introduces a wealth of new graphical possibilities.

For the game-makers, the so-called Live Create "what you see is what you play" editor, showcased in the trailer, should make the process of cross-platform development that much easier. Changes made engine-side are duplicated on both consoles, in real-time. Not only that, but the scalability elements of CryEngine 3 make it simpler for developers to write for the current generation today, while maintaining an easy path for supporting the forthcoming console platforms.

"With CryEngine 3 we are releasing the best development solution available today and tomorrow," says CryTek CEO/President Cevat Yerli. "With its scalable graphics and computation it is Next Gen ready and with new features like CryEngine 3 Live Create the best choice for game developers and companies developing serious games applications alike. It is the only game engine solution that enables real-time development."

It began with a seemingly innocuous notice in Japanese games magazine Famitsu, where special mention was made that the PS3 version of Platinum Games' forthcoming Bayonetta is not being handled by the original developer. Quite why Platinum isn't at the conn for the conversion to the Sony platform remains something of a mystery, but the recent Japanese demo release offers some potential reasons, and it too highlights prominently that Platinum is not responsible for the port. So, is this a simple case of giving credit where it's due, or is the developer effectively disavowing itself of the PS3 version of the game?

It has to be said that there is much in the PS3 rendition that Platinum would most likely wish to distance itself from. In terms of raw performance, both Xbox 360 and PlayStation 3 games have their issues, but by virtually every criteria it is the PS3 version that comes off worse, as you can see from the media Digital Foundry has prepared. There's some Face-Off style comparison shots to gawp at, along with this 720p movie:

Comparison video of the Japanese Bayonetta demos... Click on the full-screen button, or the EGTV link below, to view in HD.View this video on EGTV

The game's engine-driven cut-scenes are intricate in detail and offer a close-up view of some of the more obvious differences between the two versions. Right from the off, it's clear that the PlayStation 3's lack of unified memory pools has been an issue for SEGA's conversion-smiths: texture quality is pared back significantly. More than that, frame-rates are considerably lower, and tearing is far more frequent. There is also some evidence of the normal-mapping having a quality edge on Xbox 360. Platinum appears to have deployed one the Xenos GPU's unique compression modes (DXN/3Dc+) for a higher-quality finish, whereas the more standard DXT texture compression can look a bit rough on SEGA's PS3 version, in particular with blocky artefacting on curved edges.

Making matters worse, the developers have enveloped the PS3 cut-scenes in an almighty blur, which magically lifts the moment the gameplay begins. It's almost as if SEGA were replacing engine-driven cut-scenes with pre-rendered video sequences - only the immensely variable frame-rate and lack of compression artefacts suggest otherwise. For its part, Xbox 360 appears to be employing more selective and sophisticated post-processing, which looks cleaner, but it's clear that there's some washing out of detail and crushed blacks.

Into the game and those basic image-quality differences do not seem quite so pronounced as in the cut-scenes, but it is clearly obvious that detailing has been pared back. Bayonetta appears to be adding an extra detail map on top of the existing textures and when the base art is of a lower resolution, the difference becomes self-evident. However, by far the most obvious differences are in terms of the frame-rate and the level of tearing. There is a night-and-day performance issue here. Let's kick off with Platinum's own work on the Xbox 360 build:

Xbox 360 performance. Bayonetta's fast action, large colour palette and high levels of detail send even the best h264 encoders scurrying into hiding...View this video in HD

Frame-rates are high here, but tearing is an issue. What is interesting from a technical perspective is that there is screen-tearing that is impossible to programmatically identify. The technique for doing so involves comparisons with the frame before and the one after - finding identical video data to locate the tear. In a small sampling of cases, there is no identical video data, but the frame is still torn. What this most likely means is that Bayonetta sometimes renders frames faster than 1/60th of a second, for reasons unknown (WipEout HD appears to do the same on the odd occasion). It also means that to the human eye the game tears slightly more than this graph tells you.

There are no such troubles of that ilk in analysis of the PS3 version, which runs with a clear performance penalty:

The PS3 version of the game is still a lot of fun based on this demo, but the performance compromises are significant.View this video in HD

With more torn frames (anything up to 70 per cent in challenging scenes) and fewer frames rendered, the overall sense is that Bayonetta PS3 is a workman-like, adequate rendition of what Xbox 360 owners are getting. It gets the job done, it's still plenty of fun, all the rich imagination in Platinum's concept is there, but it's definitely a less impressive rendition of what's looking to be a great game.

Over and above all of that, this demo raises as many questions as it answers. The two samplers have overlapping content, but also go their own way in a number of respects. Platinum's own 360 code offers up sections of two stages: The Falling Clock Tower and The Angel's Metropolis. PS3, meanwhile, completely avoids The Falling Clock Tower and extends the titanic bridge battle from the other stage. A bonus boss fight (seen at the end of the PS3 performance video) is added too: conceptually lovely as gravity is thrown completely out of the window, but less technically challenging than the omitted 360 content.

Regardless of the technical challenges, one thing is common to both versions of Bayonetta above all else. The game is crammed with a wealth of wonderful ideas, new graphical scenarios and some literally insane fighting action. Hopefully the game's Western audience will get a good look at it soon.

Forza Motorsport 3 is due for release at the end of this month, and while we're reserving some time for a tech analysis on the full game, the recently released playable demo also offers up a number of decent performance metrics, some neat tech stuff, and a number of interesting decisions by the developers at Turn Ten.

A quick analysis of the in-game 60FPS mode throws up a couple of interesting graphical quirks. First up, you might notice a stippled "screen door" effect on all the surrounding vegetation: a similar effect is in play on SEGA Rally. This is known as "alpha to coverage" and it's a low bandwidth method of giving some kind of transparency. You can also see it in effect at the overpass near the end of the circuit.

The effect has almost certainly been included to help sustain 60FPS. Literally rendering fewer pixels helps contain overdraw, while the framebuffer format might also be important. On some of the formats supported by Xbox 360, transparent so-called alpha pixels take twice as long to render - not good when you're looking to maintain a smooth 60FPS.

Forza's reputation for 60FPS gameplay remains virtually unblemished in this analysis, with just one minor slip during the action. The other blips are reserved for switches between the game cameras; basically unnoticeable during gameplay.View this video in HD

Also interesting is the inclusion of what's known as a negative LOD (level of detail) bias. In the normal scheme of things, high resolution textures are reserved for areas of the game world close to the player, with lower resolution assets deployed further away. In the case of Forza 3, the road textures detail levels are much higher than they need to be for the available resolution, and this results in some superb definition at the expense of some shimmering as the detail is downscaled. Quite why Turn Ten has opted for this method over some kind of adaptive anisotropic filtering is a bit of a puzzle bearing in mind the relative paucity of the 360's texture cache – it may well simply be the case that the developer had the GPU time to spare.

HDR tone-mapping has also been included, although its usage is somewhat muted, presumably to stop over-the-top lighting effects affecting the gameplay.

Analysis of the game's replay mode suggests that Turn Ten has taken a leaf out of Polyphony Digital's book and has opted for increased detail and effects, sacrificing the 60FPS refresh rate in the process, on the track-side cameras at least.

A rock solid 30 frames in the replay sections, though a soft v-lock appears to be in play. On scene changes in particular you get the odd torn frame. View this video in HD

At this stage of the game, superior motion blur effects are added, anti-aliasing is upped to a smoother 4x MSAA and interestingly the game runs with a soft v-lock at 30FPS. In this particular replay you don't see the effect much at all, but torn frames can crop in here, particularly on scene-changing moments. On the final game it'll be interesting to see how the engine copes on really challenging scenes. Also intriguing is that the alpha to coverage effect looks different in the replays. Combined with the mask generated by the 4x MSAA, it has the bonus of adding additional colour shades.

However, as some have pointed out, it is very curious to note that the car models employed in the replay mode are not of the highest quality (judged by the standards of the models elsewhere in the demo). The angles shown of the cars at the beginning of the actual race employ the highest LOD (level of detail) models, whereas the replay shows significantly less detailed meshes for the vehicles. In all honesty, this is a bit of a mystery, maybe even a bug that will be corrected in the final build.

Check out the detailing around the headlight. The replay model (right) appears to be using lower detail 3D models when compared against the intro cameras on the actual gameplay (left). Very curious and it could be a bug in the demo code.

Onto the issue of crash damage then, and it's interesting to see how Turn Ten has implemented its model. The car has been divided up into different sections, and each has a pre-determined, incremental level of damage, with a number of removable parts. In the course of general racing, the effect is fairly realistic, but it's still somewhat removed from the reality of a high-speed crash during a real race. There's no deformation along the lines of Burnout Paradise, for example, and even the dynamically generated "battle damage" in the Xbox 360 version of Burnout Revenge hasn't been replicated.

Attempts to play Forza 3 as though it's Burnout show both the strengths and weaknesses of the damage model.View this video in HD

So, what's the big deal with crash damage any way? The bottom line is that it's a hugely important part of games that purport to be racing simulators. High speed racing is synonymous with danger, and risk must carry the threat of dire consequences... the days of ramming opponents with impunity and bouncing harmlessly off solid walls should be well behind us. The danger principle is one of the core philosophies behind Burnout, and it is interesting to note that the Criterion game's over-the-top, enhanced crashes are still vastly more realistic graphically than anything seen in Forza 3.

Interestingly though, Forza 3's model appears to have much in common with the latest work by Polyphony Digital on Gran Turismo 5. While our first impressions of the crash damage in GT5 at gamescom were not so positive, recent footage from the Tokyo Game Show suggests that Polyphony has made big, big improvements over the GC code. Removable body parts have been joined by localised damage. Whether it is dynamically generated, or pre-determined like Forza 3 is something we won't be able to confirm until there's better video or preferably some hands-on code to analyse.

It wouldn't surprise us at all if the damage is indeed pre-determined on both games. The Burnout titles have the luxury of using non-licensed cars; Criterion are the lords and masters of their creations and can do with them whatever they see fit. Both Forza and GT5 don't have that luxury, and it may well be the case that the developers need to get manufacturer sign-off on all the in-game representations of their vehicles. Detachable parts and pre-determined damage would be a convenient solution.

Forza Motorsport 3 is an impressive-looking game. Chances are that you've played the demo and you're as impressed with it as we are. Fingers crossed we can get a closer look at the final game pre-release...

Many thanks to Alex Goh for his input into this feature.