Updated one of the screenshots with the controls. That should hopefully reduce some of the confusion.
Differentiating between the enemies who are spawning and the ones who are already in the game sounds like a good idea, I'll add that to the list of changes to the non gamejam version of the game.
Doesn't shadows get bigger when the object which is casting them is closer to the light source? Kinda like this(sorry for my crappy msPaint skills).
Although the shadow should be more transparent when the enemy is higher up.