When Civilization IV came out - and I'm using the z spelling with the same counter-intuitive courtesy that allows me to refer to drag acts using "she" - it was difficult to say, "Hey! Everyone! This is the big new thing that makes Civ IV the one game in the series that'll make you guff up your lungs, in a way none of the others previously did!"
There was religion, but Civ's a balanced and even-handed affair, so religions were slotted neatly into the tech tree. Moreover, like political systems, each one was a viable gameplay option. And not, as a petty-minded athiest like me was hoping for, an inexorable mental journey from storm-worship to rocket-fuelled godlessness.
Other things changed the game, too. You could open your borders up as part of a diplomatic deal. This is something that was removed for 2008's boiled-down console and handheld version, Revolutions, and the return to the old ways was immediately jarring, making you feel that the new way was indeed the right way.
Great People were introduced, too, giving the series another way of plugging into (and generating interest in) history. But it's difficult to grab headlines with something as cerebral as Sid Meier's Civilization. Having Leonard Nimoy narrate your progress along a tech tree is about as gimmicky as it gets.
So, there we stood. Civilization IV, a critically acknowledged pinnacle of refinement, a homage to itself, and supported like clockwork with the usual strong expansions. Instead of developing itself into a where-next crisis, however, Firaxis has simply moved people around, given fresh young blood Jon Schafer the lead design role, and the unexpectedly eyebrow-raising result is Sid Meier's Civilization V.
Only eyebrow-raising to the fans, of course - this isn't Modern Warfare 2, and the two dominating responses to Civ V will be enthusiastic curiosity and utter indifference. But the attempts to win over the Civ-averse continue, with Civ V taking a few tips on approachability from the console version, all the while preserving the formidable, complex core that attracts the long-term Civ fan.
There's probably been a screenshot by now, so you might already have noticed - hexagons. Finally, Civilisation does away with right-angles. No more grid, where moving diagonally always felt a bit cheaty, being 41 per cent further than vanilla points of the compass. From a purely aesthetic point of view, the hexagons allow for less abruptly contoured land masses, and less crooked channels of water. No-one needs convincing. Two minutes into looking at the board and I've already resigned squares to history.
Hexagons can only simplify the flow of the game - each tile his just six neighbours now, instead of eight - but how much will only come out with a playtest. In the meantime, it's just another tessellating shape.
However, the way the tiles are used is changing as well. They're still a source of resources - rewarding their owner with gold, production, food - and workers will still build improvements to boost that output. But cities no longer expand their area of influence in concentric, grid-based attempts at a circle. Instead every tile is individually painted your civ's colour. One at a time.
Your expansion is still earned by increases in culture (and can now be bought with gold), and you'll earn the tiles as quickly, overall, as your previous empire would have expanded. But now, the permanent and steady expansion and shape of your empire is a more irregular, important and tactically considered process.
The introduction of City States opens new routes of diplomacy. City States are sub-civilisation NPCs which provide bonuses to any player earning their alliance. These bonuses can make them worth defending or reclaiming should they fall to another civilisation. It's also possible that the benefits of diplomacy will be outweighed by their position: a city state too close to your town might need to be destroyed. If you don't mind the reputation as a butcher.
Hands up, then, everyone who's used a strategy that involves piling up stacks of military units and ploughing your way across the board like a poker bully pushing his chips all-in? There's no shame in it. You do what works, especially on the harder difficulties. But Civ V has a stack-blocking new limitation, inspired by Schafer's love of 1994's Panzer General - one military unit per tile.
It's game-changing. Both in terms of WYSIWYG transparency and the tactics required of you. A front line backed up by ranged units, with terrain offering the usual adjustments. There's also a limitation on resources discovered in the field. Previously, if you found horses, it was a bottomless well of horses (thankfully not literally) but now you find a specific number - and once you've used them to make cavalry units, they're gone. Just as artificial, maybe, but another limitation on your war machine.
Not that Civilization is all about war - military domination is just one of the ways of winning. The othe methods - tech, culture, and so on - are still available to you, and the reasons to pursue them are more compelling.
You can't trade tech any more, but in another example of how gold takes a more upfront role, you invest in research agreements. This provides both civilisations with a research bonus to use as they see fit - not necessarily in the same area. It keeps you interested in your alliance, and saves you having to check to see if you can sell anything you've just learned to anyone else.
For a company that's all about the gameplay, there's a staggering amount of work going into Firaxis' presentation of the new leaders. No longer boxed heads - or the cartoons of Civ Rev - we now have fully modelled world leaders, roaming fully modelled rooms, speaking their own language (whether you understand it or not), with research into the body language of different cultures reflected in their animation sets.
To watch people fussing over the fibrousness of the tassles hanging from an epaulette, is to wonder whether a company is being self-indulgent - but this is another thing, like hexagons and open borders, that will quickly become an expectation rather than a waste. I've only spent a day at Firaxis, and already Civ IV feels archaic.
The new game is being written for the community, too, with an easier-than-ever map editor coaxing casuals (if there is such a thing as a casual Civ player) into the world of Civ-modding. And if you're not so inclined, a mod browser and installer has been integrated into the menu system. This is the developer's way of removing as many obstacles as possible between the less tech-savvy or simply unaware player, and excellent free content such as the complete fantasy revamp, Fall From Heaven.
Former modder Jon Schafer is unable to expand on any moderation policies for now, but is keen to point out that this is an additional service. You'll still be able to do everything the old way if you pop omnidirectional boners when manually extracting zip files.
Meanwhile, the AI is getting a new system, based on flavours. A leader has certain predispositions, towards offence, defence, recon and military training. Leaders will have favoured units, win conditions, methods of growth, and resources. They might prefer generating great people, or wonders. Queen Victoria, for example, will generally have strong flavours towards naval growth and sea-faring units. But every time you meet her, there'll be random elements in those flavours that will make her capable of surprising you: and if she finds herself land-locked, she'll adjust her priorities.
There are four layers to the computer's AI, each operating at a different level of strategy. From the Grand Strategic AI which governs which win conditions to aim for, the economic and military considerations of the Strategic AI, down to the Operational AI which moves units around, and the Tactical AI which kicks in at the combat level - to see the flowcharts as a layman is to go briefly mad with possibilities.
But something that only really struck me after watching the demonstration, taking notes and going home to have another scout around Civ IV, was the organisation of the icons on the screen. With your options aligned along the left-hand side of the screen, rather than in a blue-backed panel on the bottom with swathes of empty space around square icons. The most common use of the unit (say, Build City for Settlers) is bigger than the rest, and lesser used icons (say, delete unit) are hidden in a sub-menu.
Put simply, Civilization V is the best of both worlds: more approachable, less opaque, but still with a huge, impenetrable brain throbbing in the background. The only thing now is to play it, because it's impossible to see the changes and not want to try them out.
Sid Meier's Civilization V is due out on PC this autumn.