the trick with zero UI is, there has to be a way to inform the player how to beat the enemy. It's frustrating to keep trying different keys or mouse clicks without any apparent effect. i understand that you want to stick to the theme though. and i respect that. it's a huge challenge. i think i've only found one game among the submissions I've played that literally uses NO UI. mine uses UI for sure - i simply couldn't figure out to avoid it for the type of game I wanted to make.