Desktop Thievius Raccoonus
Very little is known about the Desktop Thievius Raccoonus, and one can only find information on it on the original Thief.net website and the Sly Cooper Wiki. According to Thief.net, you were able to download the Thievius Raccoonus and read it on your computer. You could then unlock more pages to the Thievius Raccoonus by entering codes from websites, magazines, and more. According to the Sly Cooper Wiki, the game was released in 2003 on SlySchool.com (now defunct) by Sony Computer Entertainment Europe to promote the release of Sly Cooper and the Thievius Raccoonus. The program was part of a competition in which players submitted their high scores in an attempt to win 4 VIP passes to Disney Land Paris.
While an archived version of the site does in fact exist, I could not locate a download for the Thievius Raccoonus. However, I did locate a download entitled "sly_page_1.exe" which I think may have something to do with the game. Unfortunately, the program wouldn't run on Windows XP or Windows 10. If you would like to give it a shot, you can download it here.
If you have a copy of the game or manage to get the sly page to work, please contact me at SlyCooperNet@gmail.com - you'll be a hero. For now, you can check out some screenshots of the Thievius Raccoonus game below