Evolving Artificial Life
Critterding is a "Petri dish" universe in 3D that demonstrates evolving artificial life. Critters start out with completely random brains and bodies, but will automatically start evolving into something with much better survival skills.
Machine Learning approach to Go
Artifical World simulator, it simulate virtual 3D world and execute IA programs. It have API for programming IAs in C++. it use Irrlicht as 3D engine.
Brainless is a winboard/xboard chess engine developed in C++.