Yeah honestly I made the enemies deal way too much damage compared to the score you get from killing them.. I have managed to beat the game a couple times so it is possible but it solely relies on gaining enough xp in time (spamming space as much as possible tbh) and being lucky enough by getting a few op upgrades (Melee directions is good since it allows you to attack both in front and behind, and eventually in a circle around you). You can usually gain enough time by picking the option to gain more score in the 'shop' to view the screen again to 'reroll' your upgrades.
Sorry about the balancing aspect (we didn't have the time to properly test everything), but thank you for trying my game!