Along with finishing a handful of various items, power-ups, and movement mechanics, I've also began piecing together an upgrade system and interface. There's a persistent "currency" in the game, which I'm currently referring to as gems and will be used to upgrade your character's ship. I'm also thinking I may take a Souls-esque approach to the currency, having you drop the gems where you "die" (technically, there's no death in this game) and forcing you to retrieve them on your next run or lose them forever. We'll see if I have time for that.
Anyway, the mechanics of these upgrades are still being fleshed out (the names are placeholders in the meantime), and will likely be finished when I post another update. Should have something more like a video or GIF to share next time.
Hope everyone else is making great progress with their projects as well!