Free chess software for linux

ChessX is a free Open Source Chess Database for Linux, Windows, and Mac OS X. The project uses Qt library to create modern, portable graphical interface. Current development is aimed at providing full featured PGN database. Afterwards we will add more flexible native format.
History
The project was started after development of Scid halted and contact with the author was lost. Initially, ChessX was to be a community maintained version of Scid called "New Scid". However, after some initial development, it was decided to break away from the old code so that new ideas and modern interface can be implemented.
Main features:
- Multi-platform. Supports Linux, Microsoft Windows and Mac OS
- Read-only support for PGN Files
- Work with multiple databases simultaneously
- Browse games
- Navigate through game, including variations
- Copy/Paste FEN/PGN
- Enter moves, setup board position
- Basic header search (click on columns in GameList header)
- Player database with picture support

mChess is a simple cross-platform email chess program.

The aim is to be able to play chess with your friends via email using a nice user interface without having a chess board standing in your living room for weeks.

BabyChess is a chess program. You can edit chess games, play chess on the internet, and play locally against engines.
BabyChess is distributed as free software under the terms of the GNU GPL.
Main features:
- Games between humans and/or engines can be played in the match window. XBoard engines are supported.
- The chess position editor lets you edit a chess position, and save it in FEN notation, as used by other chess programs.
- The chess game editor understands PGN notation.
- The game archive editor reads PGN files that contain any number of chess games. It displays a list of all games and lets you edit those games using the game editor.
- The ICS client connects you to an Internet Chess Server and lets you play games against human opponents.
- The "evaluator" of BabyChess is a chess engine that uses its own communication protocol. It is not an XBoard engine. This program is given a FEN position as an argument and analyzes the position. During the thinking process, information about the current best move and more is written.
- The game editor uses the chess evaluator to analyze chess positions.
- Internally, the evaluator uses 64 bit numbers even on 32 bit systems, meaning it is possible to analyze more than 2 billion positions on PCs.
- This program implements an XBoard chess engine. It uses the evaluator as a backend.
- In addition to the standard algebraic notation (SAN). French, German and Dutch notations are supported. Figurine notation is also supported, also the current fonts dont make it look good. New notations can be created.

Ruby Chess is a chess game implemented in Ruby using GTK2. Ruby Chess project has a good artificial intelligence that is heuristic-based and stochastic.

PicoChess project is a small chess program.

PicoChess will support one and two player games, as well as playing against itself. It can also load and save games, and export transcripts of games.

ChessTask project is a tool for generating chess tasks.

ChessTask is a frontend for easily creating chess tasks with LaTeX. The tasks are stored in a list which can be exported, either into a LaTeX input file, or into HTML files.

glChess is a chess game with 3D OpenGL graphics.

An open-source 3D chess program. It uses openGL and gtkglarea (from GTK+) for the rendering and is designed for use in unix.

It will soon be able to be played over network much like xboard can currently. It has tentative support for computer play. Playable against a human or against "crafty" AI.

w3Chess is a Web- and Mail- based chess board. I built this to play chess over Internet with my friends. If you play chess via E-Mail, you have several problems:
- You need a chessboard in your house for every opponent
- You could drop your board down an loose the actual piece positions
- You can set a piece wrong and your boards doesnt look like your opponents one anymore
I searched for such programs but the I only found chess-servers, or tools which depends on sql-databases and javascript.
But I hate Java-Script and I hate huge dependencies for small solutions.
Main features:
- few dependencies (its written in c)
- high compatiblity (its written in c, should also work under unfree Gaming Systems from Redmond)
- it should run fast (its written in c)
- it should need less system ressources (do i have to say it ?)
- it should display the actual board via (any) Web-Browser (no JavaScript, even lynx should do it)
- you should have the moves stored at home (E-Mail-Notifications....)
- you shouldnt be able to do wrong moves
- you shouldnt do moves if it is not your turn
- the administration should be easy (old games are removed after nn days)
- the usage should be easy (no "cosmetic" features, easy translation)
- you should be able to search for an opponent
- your pieces should be at the bottom
Supported languages:
- German
- English
- Italian, thanks to Carlo !
- Brazilian Portuguese, thanks to Fabio !
- Spanish, thanks to Pablo !
Enhancements:
- charset-Tag in Mail-Header