I completed the one level in v2, and found it pretty fun. Damage Shield seems critical, due to the enemies constantly surrounding you. Not sure if you'd want to fix this by creating more safe spaces to run to (like the endless scrolling Survivors games) or just embrace it and make the other weapons more omni-directional?

Also the EXP scaling is pretty aggressive, where missing two or three shield drops seems to be enough to scrap a run even at max research. I'd suggest maybe cutting the Exp Increase drop and then make the exp requirement scale less per level.