Really nice game!
You did a lot of things really well and the game has a nice cohesive theme and gameplay loop.
I'm sure there are lot a of great things that you have planned for this game but haven't gotten around to yet.
Here are some of the things that felt a bit off for me:
-The precision upgrade mostly just felt like a negative, once you have a lot of arrows nothing is getting through anyways.
- The damage boost rendered most of the elemental upgrades somewhat useless. Not sure about the best way to fix this, I think maybe adding a negative like damage + 1 but firing speed is reduced.
- Speaking of Elemental upgrades they are very different in terms of value:
-- The Acid is S tier, it honestly just makes the game way too easy once the player has upgraded it alongside firing speed and additional arrows. I would consider adding a timer that limits how often the pools can proc on enemies.
-- The Fire is OK, balance wise its pretty strong (A Tier). I personally didn't like using it mostly due for clarity reasons. It can be difficult to tell if an ignited enemy isn't dead or just died, this lead to some frustration.
-- The Ice Upgrade is a straight up downgrade (Garbage Tier). It offers no damage and even worse is blocks your own arrows which lowers your overall dps. I would swap the collision box for a larger slow zone (trigger) that reduces the enemies movement speed by ~50% while they are in the zone.
- I think the end-game would be better if the fight lasted for longer but the portal had a healthbar so it could take a few hits instead of resetting the whole fight because a single enemy slipped through.
- And last but not least the clones are really only useful as a early detection system so you know what direction the portal is going to be attacked from next. They literally do nothing else mid-late game. They would feel much less arbitrary if they were more useful, an easy fix would be to give them roughly 20% of the players upgrades. This would probably also mean that the difficulty would need a slight boost of course.