Billiards is a cue sports simulator. It aims for physical accuracy and simplicity. It should be useful for practicing billiards on your own and against your friends when a real pool table is not available. Both a pool table and a billiards table (that is, with and without pockets) are implemented, allowing you to play eightball, nineball, and carom billiards games.
Aviation is a flight simulator meant to be somewhere in between accurate but complicated simulators and simple toy simulators that don't provide any level of realism. It currently features a non-linear flight model, a configurable atmosphere and sky model, and a CLOD triangulation engine for the terrain. Currently Aviation allows you to fly around in an area of around 600 square kilometers centered around the Columbia river. It can be easily extended to implement combat or air race scenarios, for example.
Airrace is an air race game where the player is required to pilot a plane through sets of pylons in a prescribed order. The flight model is pretty realistic in that it features most of the effects that make flying an aircraft challenging but without having to worry about what several dozens of buttons on the dashboard do. Right now, seven training tracks and five race tracks are available. Airrace has been written on top of Aviation and Techne.