BZFlag is a 3D, multiplayer, tank battle zone, capture the flag game that pits players against each other in a networked environment. It runs on Windows 95/98/NT/2000, Linux, MacOS 10.x, Irix, Solaris, and others. An OpenGL accelerator is highly recommended, but it is playable with 3D in software.
Flight Navigation Planner lets you make flight plans based on known airports, navaids, fixes, or cities. You can use the sectional charts, wacs, or the vector/terrain planning charts. It calculates headings, winds, time, and fuel. It features Airways-based Auto-Routing, Climb and Descent calculations (a/c type based), Fuel Stop Planning, Auto-Route around MOAS and Restricted Airspace, Hi-Res Weather Radar Overlay, Viewing of current sectional, wac, and IFR charts, the ability to see a route over TFRs, detailed nexrad radar overlays over your routes, Terrain Profiles with cloud ceilings, and the ability to upload flight plans to GPS.