Do I have to choose games releasing in 2015, or can I pick games from their complete libraries 'til now? Assuming the former, I'd pick:
Wii U : Xenoblade X
XOne: Forza 6, if it releases this year; else: FF XV if that one releases this year; else: Project Cars
PS4: GT 7 if it releases this year; else: FF XV if it releases this year; else: Project Cars
But there probably are other games releasing in 2015, that I'm just not thinking about at this moment or that haven't been announced yet, that I could prefer to the games I listed.







