Half Life games... (Half life, Half life 2... Opposing Force, Blue Shift)
proof : http://www.youtube.com/watch?v=hk4kX9WEcZA xD
and other one with "speed run" :D
and for the normal one...

Sega Classics game... :P

Home

Karateka

Shank

DLC Quest

The Adventures of Shuggy, 100%ing it can take 11 hours though

McPixel (1.5 hours)
1.5 hours? With Free DLC? You are damn fast.

I can't say, I am not even close to completing 1% of any game I own, I am a little disappointed though

"McPixel" Bobo, I'm afraid I've lost all respect for you. :(

That said, Star Wars: Dark Forces. I seem to recall being able to speed through that a few times.

cool

The rest of the Exceed series.
FTL -> well, a single playthrough stays below 4 hours . If by finishing you mean winning, this one drops off the list though ;)

botanicula!
and with guide, you can get perfect achievement easily.

Not sure if anyone has mentioned it before but:

FTL

The game takes as long or as short as you want it too with almost infinite replay value. Tons of fun!

Fairy Bloom Freesia

Defy Gravity Extended should be completed twice under 2 hours, which means all achievements and stuff.

Eversion is really short too, got it under an hour back when I first played it I guess...

Nobody mentioned Fortix? Can be completed in under an hour if you don't shoot for achievements. If you do, it's... holy shit, 9 hours for me.

I beat A.R.E.S. in 4 hours, but I think that includes idling for the cards too so yeah, you're good with that.

Completed Blueberry Garden in 14 minutes... for better or worse

Windosill is also a 50-minuter or so

Brainpipe took about an hour to complete, with collecting all the extra stuff it must be around 2 hours.

Caster is a dumb fun shooter, I completed it in 2 hours and a few minutes.

Got 100% in Chains in 112 minutes.

Obviously Dear Esther counts, if you're into that kind of stuff, ya sick bastard.

A game session of Flotilla never lasted more than about 20 minutes for me. But that may be only because I suck dick in it.

Each Gundemonium game can be finished in like an hour and a half. I got the second one in 23 minutes...

Hamlet can be finished easily under an hour if you use a walkthrough. And you should, because it sucks.

Home is great, can be beaten in about an hour.

Homefront is 3 hours and then some, but I wouldn't call it any more than "mediocre".

Hydrophobia is also kinda shit, but I finished it in one sitting, in about 3-4 hours.

Lightfish is fun, took me about an hour and a half.

Lume is under an hour, but it's not good and feels like a freaking demo instead of a full game.

Got Offspring Fling in under 2 horus originally, it was really fun to play through

Project Freedom took 3 hours. It's actually a decent space sim.

Each Puzzle Agent game is around 3-4 hours to get, they're really great.

Puzzle Bots was also in 3 hours, but that's counting a second rush through to get the collectibles.

The Ship's singleplayer campaign is 4 hours and so. It's meh.

TRAUMA I got under 3 hours without walkthroughs, though some consider it to be a 2deep4u kinda game. I liked it.

For the record, I finished VVVVVV in 91 minutes...

Yeah, that's all. Pick your poison; these games are all pretty good unless noted.

Botanicula is quite lovely, 3-3.5 hours long.

Unmechanical, 2.5h.

Agree with many posted...

Also;
Intrusion 2 - i did in 4 hours, enjoyed it
Poker Night, A single match my run an hour or so, will take longer to get unlocks/achievments
The tiny bang story - 3 hours

Some potential ones, but havent finished myself:
Tiny and big - grandpas leftovers (2.5 hrs)
gateways (5 hrs)
Bleed (2 hrs)
Papo & yo (2.5 hrs)
Stacking (4 hrs)

Games you haven't mentioned yourself:

Lara Croft and the Guardian of Light - 3-4 hour. After the reboot of Tomb Raider, it's the best game featuring Lara Croft.
Fortix 2 - It's fortix, but a sequel! (1-3 hours)
Portal - genious 2 hour science feast.
TRAUMA - 1 hour of cosy mystique, point and click style.
Braid - Super Mario Bros, but for brains.
Mirror's Edge - The game that got me hooked to First Person games. Took me about 3.4 hours to beat the first time I played, If I recall correctly.

Indeed DLC quest is short but fun .

it has been mentioned, but most of telltale's episodic stuff seems to last around 3-4 hours per episode depending on how deep you get into the dialogue trees.

Bastion, if you haven't played.

Eversion. I beat it 100% in about 2 hours. Addictive and charming.

Desktop Dungeons is nice and short (really, it's only like 5 minutes) with TONS of replay value :) Other short(ish) games that I can recommend are:

• Ittle Dew
• Insanely Twisted Shadow Planet
• Mark of the Ninja
• Dust Elysian tail
• Isaac
• Stealth Bastard Deluxe

Great thread, thanks for the suggestions!

Ducktales: Remastered

Only Gunpoint, Organ Trail and 10,000,000 come to mind, really. Though if you stretch your play-time to 6+ hours (a solid evening or two afternoons of gaming), then you can count in :

Lone Survivor

Puddle

Saira

Solar 2

Waking Mars

I suppose it all depends on how fast you play games. I play at a pretty slow pace and love to take in the scenery, plus the die-hard habit of combing for secrets and hidden items. I would add Swords & Sworcery Superbrothers EP or whatever it was called, but that game was absolute garbage. I can't believe I forced myself to finish it. Almost as much as I can't believe it is so loved by others. Baffling~

shank 1 (because i still have to play the second) was great, took me 3,5 hours. It's a must play like deadlight and to the moon imo. different kind of games tho, but they are little gems <3

Adventures of Shuggy

Portal 2-4 hours .

Zeno Clash <4 hours storyline , 10 hours for 100% completion