We've used GCompris at times. Good babysitter ;-) and it's educational Better than a 'boob' tube anyway.. It's pretty nice and seems well behaved. Decent audio to set the mood. It plays chess, (quite well ....more on that later), has many puzzles that are thought provoking. You can learn to parachute into a boat or drive a submarine (it ain't easy). And there alot more games.
There are a lot of games written to run on linux. Happy Penguin seems to be keeping some type of list. I play mahjongg once in a blue moon. Used to love the asteroids: think that one is only in KDE though. I don't use it. Now I see another linux version here...something interesting because it allows me to run thin clients. I mean I only need one more terminal. Might be a bit heavy though. it's linux educational software called K12LTSP meant to run a server for schools.
But if ya just wanna look without installing...the GCompris site says it is included on Knoppix. What does that mean? Well it means you can download a cd....boot it instead of your Windows XP or whatever and...teach your kid how to drive a submarine.