Here's the itch.io page: https://soldirix.itch.io/a2-zygon-demo

This is a retro-themed bullet hell with plenty of unlockables, unique bosses, and rpg elements.
It will be released on Steam early this December. I recommend you wishlist it there:
https://store.steampowered.com/app/1910490/A2_Zygon/