itch.io

oh, decker doesn't support complex musical structures, so the best way to go around that I've found is millie's jankytunes and the jankysequencer linked on that page. there's also someone in this jam forum willing to help with music composition if you want to message their board! 

As an alternative to JankyTunes which has already been mentioned, one way of getting soundtracks working within the restriction of "ten-second clips" is overriding the loop handler so it plays through a series of clips in sequence instead of just repeating one. Depending on if you'd rather record your music vs sequence it this could be an easier option. I have done something like this before so can help out if you want to go this route