I've just spent far too long writing the beginnings of a ridiculous music game for web browsers. You use either a MIDI keyboard or the computer keyboard (a s d f g h j k). The game plays a bar of random notes and you have to play it back, correct notes and correct timing. As you level up, the patterns get more rhythmically complicated. If you make 5 mistakes, game over; you have to start again. Still probably a lot more to do to make this more interesting, but I'm curious as to whether anyone finds this remotely worthwhile.
One challenge right now is how to calibrate if you don't have absolute pitch. I feel like I might need to add some sort of screen where it plays you a few notes until you find the right ones or something. For now, note that it's in A minor, A3 to A4.
https://files.jantrid.net/simus/
Simus

@jcsteh That's cute. I noticed I lost a round and a note kept playing for some reason, had to Ctrl+F5 to stop it. Are there levels that you have to play more than one note at a time?
@Jage Yeah, will try to fix that bug. Not currently polyphonic levels, but that's an interestingly nasty idea.
@jcsteh I'm here for interestingly nasty ideas. You could always implement a cord CAPTCHA.
https://bestmidi.com/captcha/cords.htm
Chord CAPTCHA

@jcsteh Seriously, it's a cool idea though and the music gives it some life. Can you control the diffficulty, i.e. make level 1 on expert start faster
@Jage @jcsteh Can you also allow for no background music? I don't think I have a chance to not lose if there's background music.
@ppatel @jcsteh Maybe a BG music volume.
@Jage @ppatel I think it'd be harder to play without background music because of the timing, unless you're very rhythmically precise. I've turned the background music down a bit though now.
@jcsteh @Jage that makes sense. I aappreciate the lower volume though. I'm one of those people who never has music on in the background when working or listening to my screen reader. My brain just doesn't work that way. It could explain why I'm terribly bad at games with loud background noises.
@jcsteh @Jage Thank you for the game. It's a lot of fun.