I once bought a game without looking at the min req's to see if it would run because it looked fun.  That game required DX11.  My PC supports up to DX10.  This is something that would make or brake me pre-ordering the game.  If it doesn't have DX10 suppourt, I won't be pre-ordering.  I pray it does have DX10 support along with a limit for the amount of RAM it can use on a system

It'll be  a cold day in hell before they restrict this to Win8.

Win7 will be fine, but that's as far down the totem pole they will be going. They are after fully fledged 64bit with all the bells and whistles, no way will they go below Win7.

Hell will freeze over before Brad goes anywhere near Vista for GalCiv III

They don't have to - it'll just be a case that GalCiv will not run win7/DirectX9.

We will see in a few weeks, my betting is still on Win7/DirectX10 minimum

Just to help clarify things more, there's two aspects of Directx 11 (or 9 or 10) there's hardware support up to a certain level of directx, and then there's the API that they use. They can still use the DirectX 11 api even if the minimum hardware they are targeting is DirectX 10, it'll just have some graphics features flagged as being unavailable. The api is available on all version of Windows from Vista upward as has been noted.

So they can code it using the DirectX 11 API and run it on DirectX 10 or 11 hardware, just with a feature difference.

I had Vista and it had DX11.

In terms of OS support everyone will be fine. Long as you're running the 64 bit version of Vista or above. Unless you're some kinds of rediculous 64 bit XP hold out, in which case, I hope that padded room you're in is really comfortable. XP support runs out in 6 months, so you'd better start upgrading.

Given that COD:Ghosts requires 64-bit, and BF4 will have both 32/64 bit versions, you can more or less bet that other devs will follow with 64-bit requirements. Given that most PCs ship with 64bit win7/win8 anyway (and that Steam's own hardware survey indicates a good 70% penetration) expect more 64bit games in the future.

For hardware support, again most people should be ok. Despite the fact that games have been lagging in the DX10/11 support, on the hardware side the card manufacturers have been building in support for those platforms for years. On the Nvidia side, DX10 support from Nvidia has been around since the 8000 series. DX11 has been supported since the 4xx series. If you meet the minimum requirements of any modern games, you're likely ok.

well, DX9 may be no longer supported by the company that made it, but I assure you that most games still does support it. My guess is hell yes it will be supported.

They say it won't be. They also say they're making the game 64 bit only, which rules out XP.

DX9 support is dying a very rapid death in the industry as XP dies off and now 64 bit PC hardware based consoles appear. If you're making a PS4/Xbox One game, it's going to be aimed at x64 with 8GB of RAM and what is functionally DX11 graphics.

Take a look at what's coming out this year, and DX9 is not everywhere. By this time next year it won't exist for any serious game.

GalCiv 3 doesn't use Nitrous. Frogboy already said so in the very thread you linked.