Well I have not yet really looked into the lighting system in Superpowers but I have messed around with it a few times and I think its still pretty buggy. I think your best bet (especially in a 2D game) is to just add the shadow in with your sprite our create a separate shadow sprite and just have it follow underneath your actor if you want it to have it own animations or you don't want it to constantly be attached to the actor for example when the player is in the air. Hope this helped or gave you some ideas for your own hacky approach! :D