Neat concept but it suffers from not really explaining what's going on. Were the yellow enemies supposed to hurt me or just block my orbs? The spikes and orbs are also way too small so it's hard to see them - I didn't know I was dropping spikes enemies could take damage on because they were so small I couldn't see them easily.
I'd also prefer if you could hold down the mouse to shoot the orbs since repeatedly clicking hurts people's hands.
Other than that though, I had a pretty good time. I think this could be really fun with some more polish.