It gets kinda stagnant after about five minutes, I feel like some environmental hazards that force the player to move outside of their comfort zone could keep the momentum going. Maybe having fireballs or acid fall from the ceiling to create areas the player cant move, or having arrows shoot out from the walls in a pattern.
Maybe some optional challenges to encourage the player to do something different, like maybe a glass cannon powerup you can get from not being able to use weapons for 30 seconds? It might not fit what you have in mind, just some extra ideas for depth.
Otherwise, the game plays very well and feels really polished! Great work \o/