Firaxis just demo'd Civilization V to us, showing off some of the new features that make this a break from the previous games. The first: new win conditions that emphasise Social Policy and Government over war and diplomacy.
In Civ 5, there are six social policies - each of which can be pursued seperately. They're almost like achievements for your empire - developing certain infrastructure, technologies or units. In the example quoted, you'll be asked to pursue the 'Tradition tree', which, as you progress through it, offers new, helpful bonuses. For instance, developing the aristocracy will help you complete wonders more quickly.
Once you've completed a number of the six trees, you'll unlock the 'Utopia Project' - a worldwide wonder that, once completed, gives you the win.
Victory isn't the only core mechanic that's undergone radical revision. Hexagons replace the square tiles, giving more natural terrain, and helping to equalise movement over distance. Multiple tilesets should help make exploration more fun - Firaxis showed specific locational sets - including Japan.
Puppet governments installed where you've defeated a city state or civilization - giving you control over what they produce, without the nasty side-effects of revolt. And in the diplomacy screen, you can to determine what their cilivization will research - by request or demand. If you particularly want to own a tile but can't pump out enough culture, you can simply buy it.
Terrain plays a much more important role in combat, particularly given only one unit can be placed on a tile at once. In the demo, Elizabeth almost withheld an attack from a much greater force by camping out at the top of hill edged by a river. It was only by bringing in ranged cannons, that the riflemen guarding the city, was taken down. We're not sure if the no-more-than one unit applies to cities, but it does mean that combat should take place on the field, rather than being stacked at the centre.
Multiplayer will be provided by Steamworks, and the game will come with an in-game mod and map browser, which should be great news for community - there are some brilliant Civ 4 mods already available.
The new interface shows an impressive attempt to make the whole system far more intuitive, without sacrificing too much depth. Apart from anything, the unit on the map is now a far more accurate depiction of actual strength and size.
But the greatest, and least noticable change? That horrible blue panel at the bottom of the screen has been almost totally removed. You can finally see how gorgeous the world really is. And then nuke its face off.
