I've got a lot of side projects like this one. The programming I do at work has a solid purpose. It's relaxing to work on something that isn't strictly necessary, as long as it satisfies my curiosity.

I like reading through disassemblies of DOS games and figuring out how things work. It's fun recognizing C programming patterns in the assembly. There's something a little charming about looking up what writing to some VGA control register is supposed to do...and I haven't found anyone else who actually thought any of that sounded like fun.

Someday, I'll put together a series of blog posts about it, and maybe I'll have some code that I actually want to show off, but right now I'm just having fun.

Or what if the purpose is "because it was fun to make", or "it was a great learning experience".