The only ones I can think of that I finished the same day as I started are the Guitar Hero games.

Most other games I like to take my time.

How about everyone else?

Me and a friend finished Metal Slug Anthology on my Wii that I sold.

Flower

Halo 3 is the only one I can think of right now. That's probably because it was so recent.

Wow... way too many.
Ill go with this gen though, Halo3, MGS4, CoD4, CoD:WaW, Gears1 + 2 and most recently Resident Evil 5

Sonic 2 like 14 years ago ^^

im a loser ! it takes me weeks if not months to finish a game.

Super Metroid. My friend and I rented it for a day....and we had to pull an all-nighter to do it. Took us 17 hours...and it wouldn't be for several years when I actually owned it that I would end up getting 100%.

The only two this gen are Braid and Portal and that has a lot to do with the fact that they were about five hours each. I can't be bothered to marathon a game any longer for 10+ hours in one sitting. I did however blaze through about 2/3rds of Prince of Persia in my first day and then finishing it up the next, so that's the closest a 10+ hour game has hooked me this gen to finish it quickly.

world of warcraft

seriously though

Trauma Center (and hard mode) (I started skipping conversation btw)
cod4
god of war 1+2
flow
half life 1+2
doom 3
pretty much any fps
even counterstrike, i beat that one so fast