Re Samurai II: Vengeance, it appears that it got pulled from the Ovi store atm., so piracy seems the only option... I played it a month ago and it worked quite well, with just an odd bug here and there - I guess they don't deem it ready yet...

As for Unity on Apollo, if it's true that it will support native C/C++ development, then it will probably be ported one way or the other, but whether it will be usable in RL it might depend on other restrictions that Microsoft might impose (namely Marketplace rules and so on). If it still remains in the interpreted .NET/XNA world, the situation would be pretty much the same as it is for WP7.