There was/is stackeless with a(n initial?) focus on game engines iirc: https://github.com/stackless-dev/stackless/wiki https://github.com/stackless-dev/stackle

There was/is stackeless with a(n initial?) focus on game engines iirc: https://github.com/stackless-dev/stackless/wiki https://github.com/stackless-dev/stackless/wiki It got less attention than pypy, but might be more pragmatic wrt parallel perf. There's also some work in pypy to remove the GIL, but not sure if there's been any news on that lately.