One of the best space simulation is available also in a Linux version.
Thirty-two years have passed since the Great war. Terrans and Vasudans have formed a new alliance. But new threats are lurking around.
Phalanx is a chess playing engine with agresive playing style. It does not have its own graphical interface, but can be used with general chess interface Xboard (Winboard) by Timm Mann. There is also a commercial version that runs as a native Fritz module and thus can be used with the Fritz graphical interface.
The FlightGear flight simulator project is an open-source, multi-platform, cooperative flight simulator development project. Source code for the entire project is available and licensed under the GNU General Public License.
The goal of the FlightGear project is to create a sophisticated flight simulator framework for use in research or academic environments, for the development and pursuit of other interesting flight simulation ideas, and as an end-user application. We are developing a sophisticated, open simulation framework that can be expanded and improved upon by anyone interested in contributing.
Toga II is a chess program, derivative of Fruit created by Thomas Gaksch. It has more chess knowledge and perhaps a better search algorithm. It is based on Fruit 2.1 and is free.