This game has plenty of potential, but it suffers from bugs, and not the good kind we fight in the game.
There are plenty of instant deaths that can happen, you can be juggled between enemies, and sometimes you can get stuck on the ice spears. Perhaps a 0.5s immunity period after getting hurt would solve this as I know there were times i would get hit 12 times in a 2 second period due to juggling.
The gameplay is solid, however it appears unbalanced, either the strength of the bugs is determined by your upgrades, or it is determined by your number of deaths, because I cleared this is two lives, without experiencing a single lvl 5 or above. Needless to say the game only took 8 minutes.
On my home computer I focused on upgrades and devoted a good hour and a half to this game and never found the exit and got to a point where virtually all enemies were over lvl 5.
Either make more levels, or include all levels of difficulty at one time per play, increasing the levels as you get closer to the exit.
Also there is a bug where you do not start at the door, if you do not go back to the door you fall through the floor and you have to suicide.