The Circular Ruins.
Not bad for 2 hours -- learning the tool (Twine) and writing whatever popped into my head. Originally the idea would be that making him talk about traumatic stuff would make him depressed and result in a sadder ending, but I couldn't figure out a framework / the code to do it, so the whole thing's fairly generic as far as interactivity.
But anyway, I heartily recommend that everyone try writing one with Twine. It's fun. Give yourself a time limit too.
You should also see what Increpare made for New Years -- another awesome puzzle game in his series of awesome puzzle games, Octat. (And Notch was working on some other game about finding metal pants in forests?...)