We created an Multi-agent gym environment call "TankGym". The implmentation is based-on the "SlimeVolleyGym" environment: https://github.com/hardmaru/slimevolleygym.
The development "sandbox" that we used in development is found in https://github.com/barrybrianbarrios/slimevolleygym. Here, one can see the commits and code revisions before the files were transferred to this repo.