As well as the games here, there's another game, The Minstrel's Song, that has its own section. Some of the open source software projects are also games. But if you're looking for an interesting challenge, why don't you try A Four Dimensional Maze?

A four dimensional maze

Some years ago, I wrote a program that allowed the player to navigate a four dimensional maze. The game looks like it did on the Apple ][—a blast from the past.

Generica (medium)
This is an icebreaker board game: if you print out the printer-friendly version, you can make your own board game to play with friends.

Genius for a Day

How'd you like to be a genius for a day?

The Minstrel's Song

A tabletop medieval high fantasy role-playing game.