Name: Sonic Pi
GitHub Repository: https://github.com/samaaron/sonic-pi
Is it Open Source: Yes (MIT License)
About / How many users do you anticipate will use this software?
Sonic Pi is a live-coding environment for music performance. It offers a text interface to sequence synthesiser and sampler tracks and process audio signals via Ruby-like code. It is a mature, well-documented piece of software that is being developed continuously and actively maintained by Sam Aaron and a team of contributors.
The project has received publicity in the educational sector, through the Raspberry Pi Foundation (who also supports it financially as far as I'm aware), and otherwise (TEDx, O'Reilly, etc.). It is regarded as an excellent tool for learning about, and acquiring practical skills in programming, music theory, music performance, synthesis, signal processing and music production. It is easy to use/get started with and includes an excellent tutorial. It's suitable for children, but also as a serious performance and music production package. It's already used live by electronic musicians. As such it has a large range of potential users.
It's also quite unique. There is nothing that comes close in terms of usability and active development as far as I'm aware. It has about 2000 Stars on GitHub, however, I suspect that most current users download the installers from the official website or via the provided Debian/Ubuntu packages.
Here is an example of a performance using only Sonic Pi: https://www.youtube.com/watch?v=rnCE7hxNGXw
I'd love to see Sonic Pi in Solus. I think it would be a valuable addition.
Link to source tarball/zip file: https://github.com/samaaron/sonic-pi/archive/v3.0.tar.gz