Development wise the game is great! Good feedback, art is awesome, shooting is satisfying.
I think it is a little off the theme, but that isn't the main issue. I think the thing that drags it down slightly is that it actually feels worse to play as you go on due to the design. Had the player been in control of the horde in a top down shooter game, upgrading the enemies suddenly goes from being annoying over time to a good thing again.
Still a great game for 48 hours!