Hi, I think your game was nicely executed. I liked the music, it went well with the art style you chose. It took me a second to understand what I needed to do and it was definitely a test of knowing keyboard shortcuts (didn't know as many as I thought I would).
What kept me from enjoying it more was feeling like I had an objective. Maybe make it a bit more punishing with the mistakes? I think that might be a good way to make it more engaging. Because if I make mistakes for not knowing the keyboard shortcuts, really that's on me. As for difficulty I think you could scale that by adding more rows of keys, or more shortcuts to shoot. If you could give ours a looksie, I would greatly appreciate it!