QMentat helps you practice mental arithmetic. It uses arbitrary-length fixed point arithmetic, and can handle any size numbers, only limited by the size of your screen (and in the case of division with an integer result, the speed at which the number can be factored). It is also quite configurable, allowing you to tailor the questions to your needs.
Galois is a computer game of the "falling blocks" type, but with unique features. Unlike most other games of that type, it is not limited to blocks made of four two-dimensional, square bricks: you can choose among several different brick shapes, blocks composed of more or fewer bricks, and even between two- and three-dimensional games.
EPIC is a multiplayer strategy roleplaying game in which you are pitted against or work with real people in various fantasy settings called modules. It starts with Conan and Malazan modules. Third parties can create new modules. The system supports adventures, armies, characters, assassins, guilds/buildings, very rich magic (over 400 spells) and over 2,000 items, in a realistic fantasy world . The game focuses on minimum game time but the maximum amount of time thinking about the game and your cunning plans with your allies. There's no farming or repetition. The game format encourages the creation of epic fantasy tales. Part of a player's turn is in real time, but movement and military orders are done as submitted orders which are processed as your turn.
Horrors of Democracy is a game in which the challenge is to introduce a system of accountability for all citizens before there is a revolution. It uses a simple economic model of the structure of many Western societies and democracy, and personal income and expenditure are modelled over a number of years.
LinRadiant is a level (map) editor for FPS games that use id Software's engines (Quake 1/2/3). It is a derivative of NetRadiant with an improved build system. It is very easy to build, even for people with little experience in software development. It has built-in support for the following games: Darkplaces, Wolfenstein:ET, Nexuiz, OpenArena, Quake, Quake 2, Quake2world, Quake III Arena, Q3MIN, Tremulous, Warsow, and Xonotic. The package contains a lot of useful documentation (mapping tutorials, technical documents, etc.) that are automatically installed and can be accessed from within the editor.