gran turismo (PSX1,2,3,4?) - any console, any time again san francisco rush 2049 (DC) - battle mode + 4 player = awesome; this often is stuck for months in my dreamcast tetris - i hated it when i was 7, now i love it metal slug - there went my allowance tekken metal gear solid and many more, but those are the titles that consumed most of my time i guess.
Sonic 2 on the mega drive was the first game that really ate up a lot of my time (and still does) Phantasy Star IV, on the MD originally and then from the PSP collection. Certainly killed a lot of long journeys for a year or so ater it came out! Resident Evil 1, i could probably play this with my eyes closed even now. And i know that i could do some goals on THPS1 without looking back in the day Both Ocarina and Majoras mask on the N64... even before i actually had a 64 myself i used to camp out at my mates house all weekend! MGS2 - European Extreme mode enough said. at the moment Fallout 3 is still eating up my time, 100+ hrs and counting... So long as they keep bringing out more DLC i'll keep playing!