Selador is a browser-based fantasy game. The game was commercial at first, but has since been released as open source by its developers. The game focuses on teamplay and communication between players. Although it is played in real-time, strategy and planning are paramount. It comes with a nice set of graphics and a pre-populated database. It can be installed on any *AMP stack.
Mindbender is a game which works like Mastermind, but is easier to use. Instead of colors, you use numbers from 1-9. It's a four-digit code you have to solve, as in Mastermind. You can set the number of tries in a separate file or you can use a small setup manager. It's a very small project.