A few suggestions:
1) Some enemies have to walk less than half of the others before they hit you because they hit the castle at the sides. You should probably have a round hitbox.
2) Enemies move speed is scaling to fast, by level 20 almost every enemy just hits the castle before you get to attack.
3) There should probably be more upgrades, like arrow speed, aoe attacks and enemy debuffs.
4) Skills needs a spell check(attack, not atack) and a description.
Viewing post in Solo Tower: Idle Roguelike comments
I'm on wave 24 now. Got there with two rare seeds in a row and 4 harvests. Enemies hit the castle anyway and armor determines how far I go. The castle reach is far and cheap enough so that the hitbox does not play into it.
Operaionally I see killing enemies and fire rate+damage only as a variable gold generator not for how far I go.
I have gone up to level 33 now. My armor is maxed and no matter my attack speed 9 out of 10 enemies run to base before i hit them and some reach the base from the sides before my arrow goes out of the base... I agree with the incremental idea, but the balance is way off at later levels, you can't tank them and you can't hit them for lifesteal!