Viricide is an internet-multiplayer-ready version of a famous virus curing puzzle game.
Viricide is currently not a native Sugar app, but since it is written completely in Python it should be easy to port.
The code for Viricide is hosted at Google Code at http://viricide.googlecode.com/
Installing on your XO
There is a specific XO laptop support page on the Google Code wiki: http://code.google.com/p/viricide/wiki/XOLaptopSupport