Earlier quoted context omitted.
No reasonable person would have been confused into thinking it was an official IKEA game; IANAL, but it seems unlikely to me that IKEA would have ultimately prevailed in court, though a simple change to the color of the logo would probably have been helpful to the devs of the game.
Yeah, that seems like the type of thing that should at least in theory be fair use.
If you don't defend your mark, you lose it.