It is a conscious decision, actually - Chris Roberts wants to go all out with the graphics, and that means he can't afford to be backwards compatible . I mean, already XP users don't have access to all the latest DirectX features, because the last couple of DX releases have been specifically for 64-bit OSes. Most games that come out today do still support 32-bit XP, for a very obvious reason - if they were too good for XP, they also wouldn't run on consoles, because both the X360 and the PS3 are now massively outdated, they were top-of-the-line in 2005. PC games today look nowhere near as good as they could, if they weren't being held back by the absence of a new generation of consoles. But if this game is going to be PC-only, there's no reason to hold back on anything.And lastly, I'm not sure that being 64-bit-OS-only makes any difference other than it guarantees that there are no limited memory address space issues that are inherent in a 32-bit OS. I'm sure Star Citizen, with its high-end-PC-only target would restrict itself to 64-bit OSs anyway, but I don't imagine this would necessarily be a conscious decision.