When I first thought about the question I'm asking all of you, I felt a little bit disappointed with myself. But after around a week of deep thinking, I just realized that it would be simpler and funnier If I ask you for advice directly.
CONTEXT Not too much, that would be boring. I co found a little company around mid 2014 when I was 16 with my amazing partner Luke, where our main focus was to build musical software. Mainly this was MIDI processing tools, speech and audio processing (synthesizers among others artifacts) but eventually we decided to turn an internal tool into a video game.
This tool was built to serve as an abstracted digital keyboard while giving us insights about the MIDI of a particular song. Highly inspired in the launchpad key and other classical tools. Not gonna lie, the game was fun to play, but back there my knowledge was tremendously limited compared to now and I was facing huge personal issues. Eventually the company died in response to my own fault.
Before concluding and launching you with the answer of rebuilding and making this and all its internal structure open source, I will let you check a post that I made around 5 years ago asking a similar question but in an indie gaming subReddit.
I APOLOGIZE if you felt bored and disappointed about the post, but I thought we could have fun together just discussing the idea.
I will also include several links showing some internal parts that you may be interested in.
RESOURCES
Alpha gameplay: https://www.youtube.com/watch?v=ALEPLulOdR8&t=15s
Basic method of MIDI processing in max for live: https://i.imgur.com/9a0vagn.jpg?1
Generated output file after simple MIDI processing of the the song "We Don't Talk Anymore (Charlie Puth instrumental only) https://i.imgur.com/u27hUMF.png
Original subReddit post : https://www.reddit.com/r/IndieGaming/comments/5j36hx/should_i_keep_developing_this_game_idea/
The playing doesn't quite line up with the music at times. If the song plays regardless of whether the keys are pressed, it would be cool if the timbre changed as the player hit the keys to make it sound more lush or vibrant.
Maybe you have this already, but it also might be a good idea to allow a metronome to play as well, or some basic percussion in the background to help the player keep time.
It would also be cool to allow a free mode where the player can jam out however they please. Since you're working with MIDI, maybe even let these sessions be recorded as MIDI files (although that might get it further away from a game and closer to a tool)
Overall, cool project.