I had an idea for a musical game for the Pico, and wanted to verify whether the idea would work within the audio limitations first. Turns out, it wouldn't - but the toy I used to verify that turned to be lots of fun and took on a life of its own, so that's a win, I guess :).
Z - add/erase notes | select options in the menu
X - change instrument
hold X - back to menu
Just put some notes on the grid to get a feel for it. You can save your songs to the cart itself, and I guess also share your crazy creations as cartridges here using that option:). There is also a demo song in there if you want to check out one of mine (disclaimer: not a musician by far, listen at your own risk).
Have fun! All comments, suggestions and ideas much appreciated :).