The Nanosaur game was not installed on the iBook's hard drive. The installer is on the iBook Install CD. If you insert the iBook Install CD and open the Applications folder on th CD you will see the Nanosaur folder. To install the game run the "Nanosaur 1.1.6 Installer" located in the Nanosaur folder.
The iBook Restore CD does not contain the Nanosaur game. If the Restore option to "erase before restoring" is chosen you will need to install the game from the iBook Install CD again.