Gears of War 2 - I went in with hopeless expectations sins the first one wasn't that good for me. Everyone was praising it like nuts, and I just found it dull. But the 2nd was sheer AWESOME.

Mass Effect 2 - Turned out way better than I hoped.

Demon's Souls because it ate my life.

New Super Mario Bros - never expected all those minigames. I still play some of them now and then.

Xenosaga Episode 3: A game that truly defines the word EPIC! Loved every minute of it, and the final hours of the game left me speechless. Amazing soundtrack too.

Persona 4: Honestly bought this game because of internet hype. I loved it so much i finished it back to back. Amazing characters and battle system. Going through P3 now.

Wii, DS or both?

The only one I can think of right now is Grabbed by the Ghoulies. I have played it through 3-4 times, but I could not reach 100 points yet.

fallout 3 (endless well until I finished it)
oblivion (same as fallout 3)
uncharted 2 (played through 3 times and I still want to play it)
gta san andreas (completed about 10 time and kept me sane during the last days on last gen)
mgs4 (amazing story and gameplay truly a masterpiece imo)

Suikoden...

Was a game in a used bin so many ages ago for a few dollars, ended up being my favorite game series of all time.

Endless Ocean: Blue World is a lot of game for $30.

Definitely Uncharted 2.

I thought I was going to complete the single player twice and then I would be done with the game but the multiplayer is so much fun and so addictive that I'm still playing it every now and then.

Also, Fat Princess. I think I played the game for around 40 hours. That's a lot for a 15$ game.

- Muramasa : I don't have words to express the awesomeness of this title, what I didn't expected before actually playing it.
- Timesplitters 2 back on the cube : The difficulty settings actually changed totally the levels playthrough. And the platinium cups were insanely hard to get. Bought it for the multiplayer first, but the SP was very entertaining
- Rock and Roll Racing on the SNES : The gameplay was a bit hard to cope with, but this was a helluva racing game, bought after a friend told me it was good ^^
- And of course, Eternal Darkness and the Fire Emblem series.