There is a list of games at SDF Public Access UNIX System - Free Shell Account and Shell Access, and I should play them all!
The page hasn’t been updated since 2012, so I’ll just copy it here:
There are several multiplayer games that you can play on SDF via the shell and clients run on your computer
xscrabble - scrabble over X11
- any SDF server
- info: xscrabble
minecraft - blocky 3D craft work
- minecraft.sdf.org
- requires Mojang client
Counter Strike Source - Terrorist/Counter Terrorist simulator
- cs.sdf.org
- requires Steam client
Garry’s Mod - Half Life 2 in a craft work world
- gm.sdf.org
- requires Steam client
freeciv - Free Civilization
- freeciv.sdf.org port 5555
- clients and info: Freeciv Wiki
SDF Mud (ResortMUD)
- mud.sdf.org port 4000
- info: wm.sdf.org/mud
- Clients on SDF:
- Type ‘mud’ at the shell
- TinyFugue: type ‘tf mud.sdf.org 4000’
- Other Clients:
- Windows: MUSHclient
- Windows (non-free): CMUD
- MacOS: Atlantis MU
tetrinet - Up to 6 player tetris
- server: tetrinet.sdf.org
- clients: http://en.tetrinet.no/tetrinet-clients-download-1.php, tetrinet at the shell
- stats: http://tetrinet.sdf.org
BZFlag - Battle Zone Capture The Flag
- sdf.org port 5154
- clients and info: http://bzflag.org
Those games should probably be noted they exist there, but otherwise get their own quests…
Quest the games