Uh, sorry for the delay :P ..Yes I have all netfs compatible versions for xp installed (from v1.1 to v4extended), plus all other runtimes like visualc, xna etc. The error, instantly on double click, say that it's "not a valid win32 application". For my knowledge, it depend by the kind of the engine code.
Yeah, as you said. Also if you get the message "not a valid win32 application" means it's only x64 compatible, so I guess you can play on Windows XP if its the x64 version.
nope... just tried on 64bit by virtual machine, but the massage is the same (other games have the some behavior too). On vm i still play many other games, some of them also declared non xp compatible as well. If your game is coded under unreal engine 4, this seems to be the solution: https://docs.unrealengine.com/latest/INT/Programming/UnrealBuildSystem/Configura... ...in any case, really thanks for your time :)
Oh and soon I will update it, I will check compatibility with older windows and 32 architecture.