There are a few text-only games installed on the shell:
- moon-buggy
- ski
- netris
tf (MUD client)
You have to be in the games group to be able to play. Request it and I'll add you right away if you have been a good user 
If you want some more games, just ask and I'll see what I can do.
Keeperx has just started a MUD of his own at Blinkenshell, you can read more about it here: Info/MUD or just start playing with this command: startmud
Have fun!