I like this take on the "only one" idea. Only one (reusable) bullet that ricochets of the walls? So basically billiard with chickens who shoot back? Pretty fun :)
Only gripes i got is that the enemies don't seem too much of a threat, cause they fire rarely. Plus the cactus doesn't seem to do any damage on contact. With some additional twists in gameplay / level design it could be a fun game for longer while :)
P.S.: where you the guy asking for how to do the bullet losing velocity on discord? :)