Ditchers is a multiplayer action game where underground tanks use a variety of weapons to find and destroy each other. Tanks dig tunnels in the soil with a limited supply of energy that can be refilled only in homes (as well as health). the GUI is controlled mainly by mouse, while gameplay is controlled only by keyboard. It is not difficult to create your own maps or to draw your own tank. The game supports split-screen, network games, and artificial players whose intelligence is programmable in the Lua scripting language. The game is inspired by Tunneler.
ca-ga is a toy artificial life simulation that uses genetic algorithms on large cellular automata. It uses simple but easily extended DNA that is 8k long by default, though you can take the size out to anything you have time to evolve. It sits under each cell of a 128x128 board and orders operations to transfer energy in the hopes of achieving a kill and breed. The simulation features a mutating fitness function, emergent sex, and a proof of concept real world fitness function. After enough generations, the cells or genes could achieve collectivism and organismhood, coordinating the values of the hotspots that determine board temperature in order to maintain a desired equilibrium. But maybe not. If you work in a fitness function, an optimizing problem solver results.