With the jam underway for 7 days now, it would be a good time to start sharing your ideas. You can create an entry earlier and update it later once you've made more progress.
What I want to make myself is a blues improvisation simulator. Jamming blues music is one of the staples of playing music together with fellow musicians. Because of its standard format and scale, anyone who knows these things even a little can jump in and join the fun that is improvising music together with other people.
Sadly most non-musicians never get to experience this, so I thought I'd try to find a way to simulate it somewhat. It's not going to be a game per se, but more an online toy / educational experience sort of thing. The idea is that I'll provide a virtual piano you can play with the keyboard of your computer. The twist is that you can only play notes that are in a blues pentatonic scale, which means that basically all notes will sound alright. To have something to play along with, I'll record a bunch of backing tracks on guitar which will provide a standard 12-bar blues framework. This way you can jam out on the virtual piano along with my guitar playing, so we're effectively jamming together :)
So yeah, that's what I'll be making. Show me what you've got in mind!