Nice entry for hard mode challenge! Your artwork is so cool!
An interesting strategy is attracting enemies to attack themselves.
The most of tutorial icons are understandable once playing. One thing I'm not sure is how to get that 25 points until I incidentally saw the collision of bullets.
The overheat state could be more clear but it's not a problem as we can know the constraints are half circle.
I don't know the meaning of that bar at the bottom of screen. Maybe an indicator of two colours?