"Update August 2018: The project is now freely available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 license"

This is awesome and very generous. I'm really chuffed you've decided to do this and I'm hoping it will encourage more people to get involved.

However... CC licences aren't really meant for code: https://creativecommons.org/faq/#can-i-apply-a-creative-commons-license-to-softw...

The ShareAlike bit probably maps closest to a GPL licence which might be what you're really after.

The Non-commercial bit is trickier. It might be that GPL is all you need. It's pretty hard for people to abuse your code commercially if they have to release the source code. However - if you really need to restrict it further then this Quora question might be helpful: https://www.quora.com/Is-there-a-license-like-the-CC-BY-NC-SA-for-software - but bear in mind "non-commercial is a very tricky thing to define and can cause problems for projects that you probably would intuitively expect to regard themselves as non-commercial.

The real benefit to releasing this under an open licence is hopefully that other people can contribute to the project. With that in mind, will you be releasing the full source code?