Very nice visuals, also creation of enemies, sfx, music and patterns of enemies attack. I really like that.
Concept with choosing upgrade and downgrade also fully fits theme!
Nice design of menu! :D
Well done!
Hmm maybe this mobs shouldn't be signaled with lines but instead a bit slower? That will give a bigger opening to hit them, but also will player will not see the lines so he will be more aware of whole screen instead of just lines. That will mix a bit pace of the game. But it's only my suggestion, making this into full dungeon crawler is great idea, and there is big potential!