Thank you! I tried to keep myself within the limitations of the NES as much as possible while making the game. As for the animation, I guess I'll have to make it faster, or maybe I could add a speed setting or something like that.
Spoiler for level 5: you are supposed to move once and wait for the tiny robot to crash into the spikes and explode, and then you can press the button and wait for the bomber to destroy the wall