I can't really do anything here other than stand on the fence. Every game has the potential to be fun. Platformer, PRG, FPS, Linear, Open World, Sandbox; every type of game under the sun, they all appeal to some part of our consciousness that likes to be stimulated.
But on the other hand, we can only get stimulated so much before we tire of it. Sure, mindless games like Prototype 2 are fun, and cooperative games like Borderlands are fun, and competitive games like COD are fun (to some - personally I hate competitive play); but in the end I always find myself getting sick of the old set pieces; especially the "You must save the world/society" trope. I want a huge, complex, varied, interesting game with a personal story; and nothing I can find has satisfied me yet.