I can't seem to jump. It doesn't use my joystick which Godot makes easy to incorporate.
I should be because the jump action is a custom one, and never came to my mind joystick controls. I think for now its only possible to jump using the keyboard.
I'm will probably release a update after the voting ends to fix some bugs, I will add joystick support then.
And just a warning, the boss is immortal, we had little time.