Very nice game, but it feels more like a vertical slice of a metroidvania.
The windows version was giving me some trouble, since the download is just a .exe, not even compressed, but consider it tested and working on Ubuntu 20.04.
The key rebinding was a nice touch to add, appreciate it.
The VFX and the background art are great, but the character art and animations seems like they aren't on the same level. It's not to say they're bad, but if something looks very good, it make normal or even good quality art look worse in comparison.
The controls were fine the dash and double jump was spot on,, though the melee attack stopping you dead in your tracks, took some getting used to.
I encountered the first boss, gave him a few honest tries, but after he fell down once, and I thought I won, he got back up and started repeating the same attack patterns, only faster and with more bullets. Died and gave that another try with the same result, and didn't try it a third time. To be honest, it has a lot of health and 2 attacks, and one of those attacks takes a while to finish and you can't attack at that time.
I don't know if the jam theme was implemented or not.
Overall it was a fun game, and I highly encourage you to enter the Metroidvania Month Jam if you like making these kind of games. You'd certainly have a more focused audience there.