I got the feeling that the author only included games that matched the OS's capabilities... It might also be because emacs is part of all UNIX-like OSes like BSD (which OS X is a derivative of) & Linux, or because the games are a part of emacs rather than standalone. Just guessing, though.

Neither does mine -- I also haven't seen it in 98SE (upgrade), Win2k, or XP. (I thought maybe I was just forgetting things until I saw your comment!)

I'd just say "Linux" (or GNOME Linux), rather than naming a specific distribution like LinuxGamers or Ubuntu. I believe I read recently that the environment (GNOME, KDE, etc.) determines which games appear unless the distro deliberately strips them out, anyway.

(FWIW, I'm using the latest OpenSUSE, and it came with a version of Tetris called Quadrapassel, plus Chess, Iagno, Mahjongg, AisleRiot cards, Freecell, GBrainy, Lights Off, Sudoku, Mines, and Swell Foop.)