Good pacing and concept! The bugs that were introduced, funnily enough, made the game easier for me. I think the concept is swapped around: During the first level there should be more bugs (because watching the towers grow instead of spotting a tiny arrow is way easier). As you progress the arrows become harder to spot and the screen becomes more obscured. More glitch effects can be added as needed. I also think the input could be more complicated, right now it's just guitar hero with 3 keys.