/tg/Station 13

Seriously, there’s so much untapped potential here. The only non-music game I can think of that allowed players to introduce their own melodies into normal gameplay was Spore with its anthem creator (which, coincidentally, was one of the only category of creations that wasn’t easily shareable online).

Imagine playing Dead by Daylight and the survivors hear Robotnik’s theme as you approach, or a fighting game where your hears your favourite melody upon your victory. That would be ebin

APB: Reloaded allowed you to play music from your computer on your car radio for every player in the vicinity to hear.

i just think in this game if you climb the jacob's ladder it should have a chance to play snake eater

There's Animal Crossing and your town jingle...kind of.

Mabinogi has a pretty extensive custom music system.

starbound lets you play on instruments using songs from files. i'm pretty sure the other players don't need to have the files in order to hear you and you can even form a band to play in sync with others. the problem is that it uses .abc files, which are hard to find. luckily the game has a bunch of them pre-installed so i can follow my friend around and play liebestraume while i watch them do all of the hard work. also if you fill your hotbar with instruments and switch between them very fast you can play the same note on multiple instruments and make your friends deaf.

there's also the custom music in SS13. it doesn't sound as nice though since you have to convert a midi and hope that there weren't too many instruments in there so that it still sounds decent when you play it ingame. but there's loads of midis out there so you can usually find one that works well enough. keeping track of those converted midis and copying them over each time is a bit annoying though.