I had a great time ! Reminds me a little bit of vampire survivors. I experienced a few bad framedrops on big waves, playing on chrome.
I didn't understand how the crystal works. It says that the monsters are attacking it, it makes a sound when they touch it, but they follow the player and the crystal doesn't seem to react to damage. I also don't know if there is anything else to do besides killing hordes after hordes. I'm not complaining though, killing stuff across the screen with 20 floating weapons is peak gamejam fun !