OP was asking about games... :P

So many candidates to choose from.

It would be 9.03M, but I'm not sure that's in the spirit of this thread--a fifteen-or-so-minute interactive memorial to the victims of the 2011 tsunami. Or Dinner Date, a somewhat abysmal "art" game where you sit around and listen to some loser whine about his life for twenty minutes. Thirty Flights of Loving is about half-an-hour, and contains (if I'm remembering it correctly) some more traditionally video-gamey elements like platforming. The hilariously inept Disillusions Manga Horror must have also been well under an hour; Backloggery says thirty minutes, which is probably about right. Judge Dredd: Countdown Sector 106 can be beaten in half an hour with some luck, but that's a digitalized gamebook. Hysteria Project is maybe half-an-hour as well; that's a "Playstation mini," so the length is appropriate.

All of those games are commercial releases on major platforms (Steam or the PSN), but hardly high-profile. Perhaps Dear Esther and Gone Home are more in the spirit of the thread; maybe two hours each? They're probably the shortest "high-profile" indie games I've played. I liked them both a lot (Gone Home moreso), but wouldn't have wanted them to be much longer, so that worked out. Now I'm wondering about the shortest AAA game I played; I suppose it's Portal, if that counts.

Wow, really? I own that game and fired it up briefly just to see the engine and fiddle for a few minutes but never actually played it. I was under the impression it would have been like Half-life length type of game or so. If it's that short that's kind of a bummer. Not a huge bummer as I got like 328492374 games in a bundle with it so the bundle as a whole was worth it though. ;)

Stanley Parable - Game is like 5 minutes long. First time I was like "What?". While it has dozens of endings, you can just finish it everytime in just 5 minutes.

The Room - Game has like only 5 puzzles, which at first looks hard, but when I realized that I have finished whole game in just an hour, I was sad.

.kkriger
Shortest FPS game I ever played.
Shortest not only in sense of gameplay but also size. Just 96KB!

Star Wars Starfighter. It took me about 4 hours or so to finish the game on hard. I didn't really feel like the heroes had an adventure due to it being so short, but if the protagonists were to bump into each, they'd just say "Yeah, I hung out with that guy one weekend. We had fun, but we're not really friends."

The Plan-around 5 minutes.

Keyboard Drumset Fucking Werewolf-around 4 minutes.

This was my choice.
Not a game, but procedural graphics have come quite a way since kkreiger hit it out of the park with their early procedural textures (for the time).

8kb:
https://www.youtube.com/watch?v=z5cFJryE_fc

Battle: Los Angeles
Highest difficulty in about 2 hours maybe... I'm not sure. But it was VERY short.

To The Moon - finished it in less than an hour .

Two very beautiful games, but way too short

Lilly Looking Through
Hardly 2 hours long

Mind Path to Thalamus
Almost 4 hours

Both short as hell.

Gone Home - Not so great game about a relationship that ran like crap

To The Moon - Great game about a relationship that ran like butter.

Also Stanley Parable. I really enjoyed that one.

Wow, a lot of these are SO short. I don't know that I've ever played any game that took less than 10 hours. The shortest game I think I've played was Papers, Please, but it had a lot of replayability for how little there was to it and I don't know how long it took me to complete, maybe overall it was less than 10 hours, but I doubt it.

I have To The Moon but have never played it.

RE: Stanley Parable: really interests me but it is good to know it is so short.

Easy! Golden Axe 1! The shortest game i have ever played, throughout my entire gaming career! Arcades, 2000, outside at a big mall, with only one coin i beat the entire game, in less than half an hour! (spamming the highest damage attack) Got the second highest possible score!