I may as well add an update, even though I don't have much to show for the time spent. I was trying to go for a platformer, but that plan kinda fell flat after a few hours of it going nowhere. So now I have to start (almost) from scratch, and have little to show for it aside from a somewhat nondescript screenshot. To quote the Dead Milkmen song, everybody's got nice stuff but me.

I kid, of course. Here's a screenshot of my progress so far. As you can see, it's still pretty rough, but I think I have a base down now.