Parin is a game engine/framework I'm working on and Joka is a utility library used by Parin. Both don't use the GC by default.

I recently added a new version flag: JokaGcMemory. When defined, it changes the allocation strategy from manual memory management to using the GC. It basically disables the "free" functions and uses new for everything. So if you prefer GC-based code, it's now an option. Nothing changes unless you opt in. The idea for this came while reading some comments on a Discord server:

I personally don't hate GC. Manual stuff is just more fun for me and it makes it easier to run games on a web browser.
GC + Kapendev = ❤️ (This line makes the post more professional)

Anyway, the trickier part of adding this was working around the @nogc attribute. It wasn't too bad, but now @nogc effectively acts like a made up @noallocation attribute for my code, which is kind of nice. It would be easier to just ignore it, but I think it can be useful sometimes, so I do support it when I can.
That's it. Nothing crazy, but it's a cool thing.
Btw, check out my new game: https://kapendev.itch.io/worms-within