Made with love for my fellow collaborators ❤️
gym has been moved to gymnasium. Moreover, the package allowing to run Super Mario Bros. isn't supported any more. Instead, Gym Retro packages many more games and is compatible with gymnasium. The only issue... is that it doesn't run on macOS with M1/M2 chips.
After much fiddling, I decided to swallow the pill and revert to the gym version I was familiar with: gym==0.21.