Name a game that you just finished in one game sesion

Ratched and Clank 2

Super Mario Bros. on the NES.

The first Zone of the Enders for PS2, GTA: Lost & Damned, Castle Crashers (not my first time, but subsequent playthroughs).

007 tommorow never dies for the PS1

Halo 3....my right eye actually got bloodshot

Army of Two
 
hated every minute of it but we sure did it

I've never done that..

Me and my friend played through the Left 4 Dead campaign locally in one sitting. It was pretty fun.

Trials HD. Finished all the tracks in a couple hours if that.

That I just finished in one session, as in recently?  None, but I beat plenty of games in one session back in the days before nearly every game had some sort of save function.

Gears of War 2. I almost fell asleep on my desk...

" Halo 3....my right eye actually got bloodshot "

Most recently, Shatter.

Call of Duty 4: Modern Warfare. At least, it felt like I beat it in one sitting.

Super Mario bros. 3 without using any warp whistles.  I finished the game with over 150 lives left =\.

50 Cent: Blood on the Sand in co-op.  It was awesome.

Portal

I don't think I've ever done that before.

never done it before unless you include flash games...

Portal.

Halo 3. Plus a little multiplayer. 

Most of the NES and some SNES games. You pretty much had to do that.
 
More recently though, Mirror's Edge and Shadow Complex.

Destroy all Humans, BiA: HH, The Godfather 2, Portal and Postal 2 all come to mind.

You have to burn the rope.

Too many to list, but a few would be L4D, Portal, GTA: Lost and Damned.

I cant really remember many off the top of my head but i do remember that i played the first Kingdom Hearts for around 15 hours the first day i had it.

The 1st Halo I played split-screen co-op with my cousin on the legendary campaign. Took us a while but it was damn fun. 

You guys are insane. I wouldn't really want to beat a game that quickly and like to take my time in games. I've gotten 100% with characters in Tony Hawk's Pro Skater 3 in short sessions. I could do it less than an hour, which also included collecting all of the stat points (which randomly generated in a variety of areas). I don't know if that counts. Technically you could say I beat the game, but if you stop after beating Tony Hawk's Pro Skater with just one guy, I think you're missing the point.

halo 3

I don't do it often...the only game that comes to mind is beating Resident Evil 5 coop in one sitting, just cause it was recent. 
 
Oh, unless you count some older games like star fox 64...though you dont have much of an option besides beating it in one sitting haha.

The original Dragon Quest and Strider 2.

Halo 3 and Gears of War 2.  I watched my friend beat Fable 2 in one sitting.  Hmm, nothing too crazy as all those games are very short.

I have never. I always take breaks and go of and do other things while playing a game. Even short ones.

Heavenly Sword 

flower

Too many 8-bit, 16-bit stuff to list, on PS1 I would beat the first spyro game in one sitting.

arkham asylum

If it counts: Ghost Squad. But it's only like an hour long. Otherwise, never done it.

" Too many 8-bit, 16-bit stuff to list, on PS1 I would beat the first spyro game in one sitting. "

I finished Batman: Arkham Asylum in two sittings but I don't think I ever beat a game start to finish in one

Legacy of Kain defiance: loved every second of it 

i would say contra and a lot of the older games as they never had saving file ways. it is hard to say since games now take a while.

Mirrors Edge and CoD4

" Doritos: Dash of Desctruction "

portal
left 4 dead
star wars battlefront 2

I don't think that their has ever been a game that I have finished in one session. The closest I've ever gotten though was either The Force Unleashed or Shadow Complex.

I have beaten a couple games in one sitting but I can't remeber them. But the one I do remeber is Guitar Hero 2. I beat all the story mode songs and like half the bonus list in one sitting on Expert on launch day. What a grand day it was.