Hey, thanks for reviewing our game! The feedback is appreciated, and we are working on expanding the orb combat mechanic for the next release. 

As regards to the enemies, we do feel that the rats are more difficult to fight than was intended, and have come up with ideas to improve the combat and tweak the difficulty. What you said about a hit flash is interesting, I think that might be a cool thing to implement and would help to let the player know when an orb has connected. Tweaks to the sound design might also help with this. 
And don’t worry, we plan to have many more levels and much more content in our next releases, this is more of a demo at this point than anything. 

Again, thanks for taking the time to share your feedback, it really means a lot to us!