I liked so much your game, good job doing the nature of the game representing the way of a bat. So I liked how the bat only can see when a sound is emitted by an enemy, but talking about level design, I think you shouldn't put many of the silent warms in places that I can't see, for example if I rested a bit, and then I flied until a point where I couldn't see in the rest place, I will use the eco, so I'll fly til the eco stops, if there's a silent warm after that place, I only can see it when I reach the damage range, and I'll die. But maybe I'm using the eco without a good plan, idk. Other than that, good idea and good execution of the game, congrats!