The longest game you've beaten start-to-finish in one sitting.

[SimuLord]

Mass effect 1 and 2. Did it for charity and raized 700 quid.

Funny you should mention charity because I've thought about doing a Desert Bus For Hope-like event this December for Child's Play, with either Skyrim (if it's playable enough at release---not even for charity would people want to watch nearly nonstop crashes to desktop) or Oblivion (if Skyrim's not ready for prime time.)

 

[SalamanderJoe]

I finished Just Cause 2 up to 54% in a single sitting. It doesn't sound much but...Just Cause 2 is HUGE!

How in the crap did you do that? I can't fire it up now to check, but I think I was at around 15% after ~25 hours last time I played.

I seem to recall doing all the missions and challenges and then doing a lot of base and village cleansing. My PS3 was literatly groaning for days afterwards. Took about 41 hours I think, though I was tired...

(On average I was getting around 2% an hour)

 

[WhiteandNeardy99]

Super Mario 64, 7 and a half hours all 120 stars and beat Bowser 3 times no cheats or glitches. By no means the longest amout of time I've sat and gamed but to total completion this is the only one that springs to mind.

 

[Grigori361]

Single sitting, Baulder's Gate 2 shadows of the amn.

No I'm not trolling, I beat that in in sitting.

 

[FinalHeart95]

None, I often take breaks so I don't wear out of a game too quickly.

Like with Halo Reach I was bouncing all over the place with missions, I think there's one I've only completed on co-op still.

 

[Stryc9]

Kirby's Dreamland on the GameBoy, took me about two hours and it was one of the easiest games I've ever played.

 

[captaincabbage]

None.
The best I have is completing both MW1 and WaW in 4 days. I feel so small!
And hey, good luck with it!

Edit: Wait. No. Scratch that. I DID do Portal in one sitting!
YES! I'm contributing!

EditEdit: And Mirror's Edge.
Suddenly I don't feel so insignificant (Even though they're both pretty short)

Bah, you can't count Call of Duty, it only take fifteen minutes anyway. XD

OT: Probably either Resident Evil 5 with my girlfriend (technically we went to bed eventually, but we got up and played it first thing next morning, we literally didn't even get out of bed to play it) or Shadow of the Colossus.
I just got completely hooked on Shadow of the Colossus and I finished it in a single, long as hell sitting.

 

[Nalgas D. Lemur]

I finished Just Cause 2 up to 54% in a single sitting. It doesn't sound much but...Just Cause 2 is HUGE!

How in the crap did you do that? I can't fire it up now to check, but I think I was at around 15% after ~25 hours last time I played.

I seem to recall doing all the missions and challenges and then doing a lot of base and village cleansing. My PS3 was literatly groaning for days afterwards. Took about 41 hours I think, though I was tired...

(On average I was getting around 2% an hour)

I kind of figured it must've taken a while like that. I guess it does seem to go up faster when you're actually doing the missions, but I keep getting sidetracked on the way there. "Oh look, another village...and everything in it explodes!" usually results in at least another hour of aimless destruction before I remember there was something I was supposed to do on the other end of the map. Heh.

 

[Soviet Heavy]

Half Life 2 in Seven Hours. What a blitz that was.

Return of the King for Xbox in I dunno, six hours maybe?

 

[DrFecka]

Well the day Reach came out my and some friends played all the Halo games chronologically all in one sitting. It was admittedly on easy mode but still, most epic 36 hours of my life.

 

[WaywardHaymaker]

One of my friends and I were really bored one day and we just spontaneously beat CoD: WaW in one sitting.

I still don't know why.

 

[Kenji_03]

Saints Row 2 if you allow for "passing out due to exhaustion" between the 5 day "eat, sleep, play" marathon.

Otherwise Plants Vs Zombies. Start to Finish without getting up from 9am-5am the following day.

 

[darth.pixie]

Baldur's Gate, Dragon Age, Mass Effect. I would have done Mass Effect 2 as well but it crashed and I didn't continue it until the next day.

I do not sleep...

 

[Trolldor]

The original Fable, doing all quests on the Original Xbox, in 5hrs and 30 minutes.

 

[ParadiseOnceLost]

CoD 4: MW The one and only game I beat in one sitting. The sad part is it wasn't my xbox since I didn't own one at the time.

 

[gfmbhsmo]

Recently i have done Bioshock 1 and 2 in one go 14 hours
Fable 3 10 hours 30 mins
assassins creed brotherhood 12 hours
halo reach 8 hours legendary

each of these have been done in a single sitting no pausing no getting up for the toilet, alowing for one handed playing because of eating

 

[CyanideSandwich]

I've only ever completed 2 games in one sitting. Heavy Rain and Portal.

 

[Magners]

MW2 on Veteran

EDIT: Halo 2 and onwards on Legendary with a pal. (Halo: CE was in 2 sittings)

 

[Andy Shandy]

I'm not sure on the exact amount of time, but I 1k'd Cod4 in the space of a day with very little breaks (most of them trying to get Mile High Club )