Inversion makes no attempts to hide what it is. It's as pure a product of video game maths as you're likely to get - and the maths, it has to be said, doesn't look too bad on paper. This is Gears of War + Half-Life 2: the cover shooting, art style and feel of the former, plus the gravity gun and playful physics of the latter.
The results? The results are generally pretty competent. It's no Gears of War, though, and it's definitely no Half-Life 2. That's often the way it goes with video game maths.
Let's look at the Gears of War stuff first. Inversion's a game about two no-nonsense street cops and their measured, fair-minded response to an alien invasion of the planet by a group of wacky menaces called the Lutadores.
With their dreadlocks, muddy tats and leathery outfits, the Lutadores closely resemble second-stringers from Stomp, and they talk like the Gorgs out of Fraggle Rock. I guess that makes them pretty terrifying, judged by the standards of most video game enemies. They tend to have the classic Gears silhouette, however - they're big, hulking chunks of muscle, forever hunched forward over their guns - and mowing them down is an awful lot like mowing down Locusts.
It isn't just the enemies that make Inversion feel a bit Gears-y. The UI is extremely similar, as is the pace of your characters' standard ambling walk, as is the roadie run, as is the cover system - although, granted, Gears got most of its cover ideas from elsewhere anyway. The weapons you pick up are oversized in a Gears sort of way - one of them even has a bayonet-thing attached to it. The rates of fire feel pretty similar, and the shattered vistas you move through during the game look a lot like Sera on a budget, but with the romantic fašades replaced with smooth (easy to render) concrete.
As Gears clones go, it's not that bad. It can't compare in terms of the polish lavished on Epic's series, and it can't match its set-pieces or level design either, but if you like to take cover, blind-fire and charge forward in head-down bursts of sudden movement, you'll be relatively satisfied by a lot of what Inversion has to offer.
And, like most things in life, it all gets a little better when you can chuck cars around. Enter the Half-Life 2 gravity gun, which in Inversion is called the Gravlink, and comes with a few Inversion-only improvements.
The basic idea is that you can fire your Gravlink at certain objects and - depending whether you're in blue or red mode - it will then make that object lighter or heavier. Boulders blocking your way? Blue them up real nice, and they'll soon be floating like soap bubbles. Turret cutting you down from a distance? Red yourself some hanging crates, and they'll slam to the ground, giving you a little more protection.
You can use the mighty science of both blue and red on the game's enemies - lifting them out of cover, say, or bringing them to their knees and immobilising them - and each flavour comes with its own little twists, too. Blue power is great for snagging floating pieces of debris (even wobbling spheres of lava or oil) and then flinging them at baddies - hence all that car-chucking fun you have to look forward to. It can also be used to trigger a ground-pound that sends Lutadores flying. Red, meanwhile, allows you to create a temporary shield - and who doesn't like temporary shields?
That's far from bring Inversion's only flirtation with gravity. The Lutadores have really done a number on Newton, in fact, and now certain sections of the game world exist inside perky little bubbles of zero G, where you float from one piece of cover to the next while enemies swim around you on all sides, doing you harm. Then there's the vector-shifting, which sees you hopping, at specific moments, from the floor to the wall, and from the wall to the ceiling. Fighting on the ceiling! Who said that current gen designers have run out of ideas?
Not all of Inversion's ideas are great, though. The zero G moments fail to put that much of a new spin on the game's cover system, for example, while the vector-shifts often don't matter as much as you'd think they would. A lot of the time, leaping between planes is really just the equivalent of turning a corner in a level, and only once or twice - and mainly towards the end of the adventure - do you get locations that truly make the most of its head-spinning potential.
When this happens, it's rather melancholic, actually. For a few minutes, you get a fleeting glimpse of Inversion's true promise: gunfights where you're being targeted from the floor, the roof, you name it, and platforming sections where the entire world has become a Gordian knot and you're genuinely left disorientated by proceedings.
Even when it isn't flinging you around, Inversion still has its problems. Its weapons may feel familiar as they rattle out bullets, but they're really weirdly calibrated, with a shotgun that's effective over surprisingly long ranges and an assault rifle that can comfortably take out distant snipers. Elsewhere, flamethrowers and rocket launchers are used a little too sparingly, and melee feels feeble and lacking in connection.
More importantly, while I can entirely understand why the same four or five character models are endlessly recycled for Lutadore foot soldiers - Inversion's trying to play in the big leagues with a little-league budget, I suspect, and I kind of applaud that - towards the end of the campaign the game starts to recycle its three or four bosses, too. And the boss design tends to be wearisome and fiddly in the first place.
Things start to fall apart as Inversion lurches to its conclusion. There's a hilariously random plot twist that, if it achieves Downfall levels of internet fame, may be the game's best bet at any kind of enduring legacy. Meanwhile, the companion AI, which has mostly behaved itself for the first two thirds of the campaign - prioritising targets, navigating complex levels and even using its own Gravlink now and then - suddenly has a complete emotional breakdown. Without warning, your good ol' partner's going down in nearly every firefight, and constantly calling out for help when you're busy with problems of your own. Who can blame him? Somewhere around the last level of the game, I started to realise that I wasn't sure I'd ever seen him actually make use of cover properly.
If you're playing Inversion in its online co-op mode, of course, none of this is an issue. (This mode's actually pretty entertaining, as it almost always is.) Given the grindiness of some of Inversion's final encounters, though, the ceaseless round of revives you're asked to perform takes a lot of the fun out of playing alone.(If you're looking for irritations, by the way, you can add the odd unpredictable death, lots of invisible walls, slightly glitchy cover-entry and a grenade indicator that only actually serves to introduce a degree of ambiguity onto the battlefield. Somewhere around here, it whispers coyly, there might be a grenade. Do you reckon you can find it?)
Once the final boss has been finished off - don't skip the end bit, by the way, as there's a sting in the tail - Inversion turns its attention towards multiplayer. Here, at least, it scores points for generosity. Alongside death matches, king of the hill knock-offs and an entertainingly buggy Horde-alike filled with spasming ragdolls trapped halfway inside walls, you get a variety of modes that actually attempt to use gravity in interesting ways - flipping the battlefield over as a reward for a killstreak, say, or offering two different arenas spread across the floor and ceiling of a single map. It makes for pleasant enough blasting, even if the more elaborate game designs often fail to come together into something that feels fair, but it's still roughly implemented and also mired in loading times.
Tellingly, perhaps, when the lead starts flying in multiplayer, it's your Gravlink abilities that you forget about first while you're merrily switching between guns and looking for another grenade to lob. Inversion's built around an interesting enough gimmick, but it's a gimmick that never quite comes into focus - and it never feel truly essential, just as the single-player campaign struggles to escape from its over-powering influences and come up with a coherent identity of its own.
A bad game? Not really: just an underwhelming one. Your pulse may quicken occasionally, but your world is unlikely to turn upside down.