I ended up beating wave 20 then thinking I could resume the run later pressed main menu, I do have a few suggestions if the game is updated, those being:
Resistant enemies: I found it too easy to poison kill enemies without even allowing them to leave stun, possibly giving some enemies resistance from poison or fire.
Fast mode: Simply a fast mode that removes the fancy effects.
Stacking skills: Instead of skills repeating on the list, to keep it clean just add a x(I)
a char that uses 2 yellows: self explanatory.
Its a good game that I enjoyed, and if you see this, thank you for making this game.