Thanks so much for the detailed feedback — I really appreciate you taking the time to test it. You’re absolutely right about accessibility. An audio game especially shouldn’t rely on mouse interaction. I’ll keep that in mind as I improve the project going forward.
The reason the game requires a left click first is because the game window needs to register keyboard focus before it can receive input. If it doesn’t have focus, the key presses won’t be detected. I’ll look into ways to handle focus more smoothly so this isn’t necessary in future versions.