Keyhole is a bullet-curtain style shoot-em-up which forces the player into confined play spaces.

I'm sure most first timers write something like this, but I ended up having much less time to work on this than I wanted to. I dramatically overestimated what I would be able to accomplish within a week. In the end, I produced only a short vertical slice. There are no sound effects, and all the assets are programmer art. I don't think it's very good, but I learned a lot and created the central gameplay feature I had in mind.  I also had fun.