Here's this project of mine, which is a game engine:
https://github.com/ZILtoid1991/pixelperfectengine
Unfortunately both the project grew to a scope where it's quite hard to maintain by a single person (especially since I have a full time job), and became more modular thus easier to maintain by multiple people. I would like to have at least one tester, but if there's someone with more capabilities that would be even better.
I cannot offer much in return, which makes things even harder, since I cannot just hire someone to do the dirty work for me. Even if it's really easy to learn the D language after some experience with any other curly-bracket language, people fear from new things, especially from having to write multiple languages onto their resume (which is said to be a bad omen in Hungary).
I'll post on social media, maybe I'll get some, but I'm also accepting tips from others.