Very nice idea, it can be expanded in so many ways.
Some thoughts:
\- some variation to the step sfx even if it is just randomizing the pitch. just to keep it fresh.
\- since we walk so much, it would be nice to have a faster speed.
\- I think that sometimes the punishment is too high, like in the level 17 if you fall the pit you get send back to level 16. It does not fit very well with the trial and error vibe that the game has. If you ask me, I think that you should only be send back to start of the current level. so no one would have fear of trying things.
\- also in level 17 it feels so wrong not be able to just shoot diagonally, I don’t know what to make of it tho.