7. The Legend Of Zelda: Ocarina Of Time (1998)
6. Battlefield 3 (2011)
The single-player mission was a decent but unremarkable FPS, but it's the superb multiplayer fragfests, across massive maps and with loads of different vehicles to crash, that turned Battlefield 3 into a full year's worth of entertainment. We still pop in every now and then for a spot of casual evening killing.
5. Fallout 3 (2008)
An immense, action-packed reinvention of the RPG genre, Fallout 3 gave you a real sense of time as you shaped your character from birth in the safety of the Vault, and then of enormous space as you sent her/him out into the vast, post-apocalyptic wastes as an adult. More than that, there's just so much to do - you'd spend a while clearing some buildings of Fire Ants, take out a Supermutant stronghold, you'd look out of the window and it'd be September.