I'm getting behind in these...need to catch up.
What is a good RPG to play for 2hrs or less?
Reading that question, I suddenly remember why I procrastinated on it.
All of them, none of them.
There are a few games that really can't be played in 2hrs or less. A LARP often takes a minimum of 2 hours for everyone to really starting getting into the groove. If we include character generation, then I agree with a lot of people who have suggested that many games can't even get through that in 2 hrs.
I'd say that the most consistent game I've had for sessions that short would be "A Penny for my Thoughts", with a close follow up being some of the minimalist games that project you into the action in-media-res...such as my own FUBAR. But I really don't think the aim of these questions is to continue spruiking how good your own games are to the wider world.
This one's a tough one...it does really depend on the focus of the group more than the game system in my experience.