Well, nobody seems to have figured the "generating" part out yet. What we've actually seen so far is crappy approximations of games which already exist (Doom, Minecraft, Quake 2).
Funny you should say that, because the AI Doom demo was 8 months ago and in that time we seemingly haven't got any closer to making novel games. This Quake 2 demo is yet again just a wonky version of a pre-existing game, attempting to be a 1:1 copy of the original, rather than extrapolating something like Quake 2 that isn't literally Quake 2 again.