p key: pause
Arrow keys: move
Space bar: Shoot(hold down for continuous fire)
Z key: Release bomb(tap z again to detonate)

This game is a simplified recreation of one my favorite horizontal shooters, Ultimate Ecology, a Japanese arcade game for CPS-2.
Boss 1:
The wheel arm is most effective.
The red laser does the most damage against you.

Boss 2:
The circle of turtles can not be destroyed, you must dodge them.

Boss 3:
Stay wide of this boss, it's movements are hard to predict.

Boss 4:
The hammer arm is most effective.
Don't get frustrated.