Nice idea but it I found it too hard.
I think you need to build the dificultyin the game from very easy to getting harder.
So start with one enemy, then when they are dead may be 2 and so on so the player can feel they are progressing and improving. Remember when you play the game a lot you get good at it. Always worth sticking some on whose not played and watch them play .
I would also prefer all keyboard options as found using mouse and keys in this sitation tricky.
Still good start to a game