Don't usually do bad reviewes...but
Heres the facts, no manual aiming system i.e. via the mouse makes the game incredibly tedious to play. You'll get shot from just about the area you can shoot from and so loose health, and then you'll die because of a, quite frankly, awful mechanic. No aiming would be fine if you had positioned every single enemy in a straight line. Second point is most games use the "WASD" control setup these days when using number keys, just a thought, but if you do make a new one, just adding these two things and you'd be surprised at the difference.