Thoughts so far:
Yay for Viva Piñata!
Brawl and Halo 3 are too low on the list.
Ni No Kuni deserves to be in the top 50 at least.
I always thought that Rayman Legends and Origins were a lot better than the Mario series. It's criminally underrated.
I predict that the top 5 will be something like Portal 2, Last of Us, Uncharted 2, Super Mario Galaxy 2 and either GTA5/Fallout/Skyrim/Bioshock Infinite (even though I only like Portal 2, GTA5, Fallout and Skyrim).