Might want to make death actually do something. You can just afk the game as it is.
Got to level 100, saw no invisible enemies. I assume this is just not implemented yet despite there being an upgrade to see them.
Defensive upgrades are useless. Need a thorn type damage to make it worthwhile. As it is, a glass cannon build is the only viable strategy.
The water animation is distracting. Perhaps slow it down so it does not draw so much attention. Also sharpen it if possible. Everything has clean lines except the water, making it look out of place.