Due to the randomness of the "Enemy picker system" was a nightmare try to balance the difficulty. I agree, it would probably have been a better idea make the enemies more like a"popcorn" style and increase the spawn ratio.
Actually, thats a awesome idea, pressing a button makes you lose a bit of time but give you more damage, that would have allowed for more aggressive playstyles... now i feel kinda stupid for no thinking on that during the jam.
Thanks for the feedback and playing the game!