Thanks!
I have been wanting to make this into a mobile game where players can upgrade their gear, and make cosmetic changes. So, if a stage gets too tough, they can grind until they can afford upgrades, without any limits.
I have played bullet hell shooters where even with max upgrades, I still can't beat a stage. Sounds like I accidentally made this game version like that, since the grind-to-upgrade mechanic is not implemented, thus it can be said all the gear is max level, for now.