How many enemies is appropriate per level?
I think it depends on how difficult or intensive to destroy the ghosts.
Would you prefer a HUD?
Do we have abilites that would be used. Or maybe items that we pick up and need to know about?
How strong should the enemy attack the player?
If there are few enemies, they should be stronger and vice versa.
How should the player attack? Would you like mouse click combat or full keyboard combat?
If I am firing a projectile I would prefer mouse clicking. If I am using melee it can be a combination of both.
How do you feel about the jump height/power? Should it be lowered?
I like the jump, I dont think that needs to be changed too much at all.