GCompris is an educational software suite with numerous activities for children aged 2 to 10. Some of the activities are game-orientated, but nonetheless still educational. These include computer discovery (keyboard, mouse, different mouse gestures), algebra (table memory, enumeration, double entry table, mirror image), science (the canal lock, the water cycle, the submarine, electric simulation), geography (place the country on the map), games (chess, memory, connect 4, oware, sudoku), reading practice, and others (learn to tell time, puzzles of famous paintings, vector drawing, cartoon making, etc.). It currently offers in excess of 100 activities, and more are being developed.
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.
Tux Paint is a simple and entertaining drawing program geared towards young children. It has a simple interface, sound effects, and a cartoon character (Tux, the Linux penguin). Along with drawing brush strokes, lines and shapes, you can also enter text and place "rubber stamp" (or "sticker") images on the picture. Tux Paint is extensible, and could be useful in an educational environment (such as a grammar, elementary, or grade school). It's portable across numerous platforms, and runs well even on slower systems like the Pentium 133MHz.
LinuxConsole is a live and modular Linux distribution that can be started from CD/DVD, hard disk, floppy disk, USB disk, or network card (PXE). The use of "console" in the title doesn't mean that it is started in "console" mode, but is meant to symbolize the simplicity of using it. This distribution is as simple to use as a game console: you can start applications without installing them. It is modular: there is a common base (device detection, GUI) and optional modules for multimedia, communication, and servers. The goal is having a very fast startup (less than 20 seconds), very good hardware detection, and many applications available (not just games).
ZDoom is an enhanced port of the official DOOM source. It features support for all Hexen editing features (including ACS, hubs, etc.), support for most BOOM editing features, freelook, jumping, and translucency support, a Quake-style console, high screen resolutions, removal of the original DOOM's limits, support for many more music formats (including MOD, IT, XM, S3M, MIDI, MP3, and MUS), better mouse support, UDP networking, and more.
Asymptopia Crossword Builder (Math/Text) is an application that runs in any modern Web browser, but does not require an Internet connection (if it is installed locally). The application was designed to allow teachers to quickly produce well-designed, challenging activities. The application features a configuration panel where the user can either enter their own word-hint pairs, or generate math-crossword problems via a single button. The math functionality generates word:hint pairs like: "four:7/x-3/8=11/8", where the hint corresponds to the problem, and the student would write the letters "four" in the corresponding boxes of the puzzle.