Robocode

Robocode is an open source educational game started by Mathew Nelson (originally provided by IBM). Currently contributions are being made by various people; officially Flemming N. Larsen and Pavel Šavara are working on Robocode to keep it current and fix the bugs. The game is designed to help people learn to program in Java or, starting in version 1.7.2, .NET Framework programming languages (C#, VB.NET, etc.), and enjoy the experience. It is very easy to start - a simple robot can be written in just a few minutes - but perfecting a bot can take months or more.