More complex problems? I'm not sure. A sophisticated camera is quite nice, but quake introduced a visibility determination solution that was used in dozens, p

More complex problems? I'm not sure. A sophisticated camera is quite nice, but quake introduced a visibility determination solution that was used in dozens, perhaps hundreds of games afterwards. It also helped pioneer modding (it has a compiled scripting language), and later on had online deathmatch with predictive netcode (so it actually worked over the internet!) and was one of the first games to support hardware accelerated 3d graphics on pc. It also has lightmaps, all surfaces are textured, and runs in software with no hardware acceleration, z-buffering, built-in perspective correct texture mapping, etc. Obviously, that doesn't make it more fun to play, but Quake was an incredible technical achievement for the time, I don't think anybody would put Mario 64 in the same basket.