Thanks for the feedback,
I will update the itch.io page of the game by adding the commands to it as soon as possible.
We used GetKeyDown because with GetKey the player's rate of fire was too high and we didn't have time to introduce a control like the ones suggested.
Actually inserting a signal of the life of the enemies or the direction in which you are proceeding are excellent suggestions to improve the gameplay.
The fact that the animation of death hurts the player is not a bug but a feature, we have decided that even that animation can hurt to increase the level of difficulty.