I like what you did with simplifying the core gameplay loop! And while the sound effects are not exactly high fidelity, they are perfectly serviceable and add a ton of charm.
The game does start chugging past 30 seconds though. I am assuming that you're instantiating each enemy every time that they appear? If so, I'd recommend you look into object pooling to make the game run smoother. Brackeys has a good video on the topic here: