Oh man, scratch! I remember using that in high school for a multimedia class thing. It's actually a lot more powerful (albeit pretty slow) than you'd think at first.
We made this sort of hybrid puzzle/adventure/platform game:
Some of it works really badly (Of course not the parts I was responsible for!), but overall I think it's pretty interesting how much we got out of it considering only one of us had any kind of coding experiences
Small platformer:
I put this together using the experiences I got from the first thing in about 30-40 minutes. So you can also have decently fast paced games.