Super Smash Bros Melee - Not because I'm one of those blokes who played it seriously but because it was the only game that I played constantly for about 8 years. And I enjoyed it both on my own and with friends.
Kingdom Hearts 2 - It was the only game that I couldn't put down until I finished it and I actually spent an entire week leveling up just so I could avoid finishing it.
Legend of Zelda: Wind Waker - I just had a lot of fun playing it.
Metroid Prime - Same as Wind Waker, but with more good memories.
Star Wars Knights of the Old Republic - Not really a Star Wars at all but this was probably one of the best games I've ever played and I played through it four or five times.
Mario Kart DS - Crack in video game form.
Kingdom Hearts 2 - It was the only game that I couldn't put down until I finished it and I actually spent an entire week leveling up just so I could avoid finishing it.
Legend of Zelda: Wind Waker - I just had a lot of fun playing it.
Metroid Prime - Same as Wind Waker, but with more good memories.
Star Wars Knights of the Old Republic - Not really a Star Wars at all but this was probably one of the best games I've ever played and I played through it four or five times.
Mario Kart DS - Crack in video game form.