I enjoyed Portal because I had to plan out what I’m doing before I act (without being pressured to act), the atmosphere of the game was legendary and I liked that little robot following me

Portal 2 has two community made “Valve Quality” DLCs. “Portal Stories: Mel” and “Portal: Revolution”. Mel seems playable on macOS at least. Revolution is basically a Portal 2 presequel. (It’s also so long I would have payed for it.)