Best Free Backgammon
GNU Backgammon houses the all powerful GnuBG neural network engine in an ambitious freeware project with a wealth of advanced options and capbilities. It is a highly enjoyable powerplay program to delight all backgammon enthusiasts and a must-have for anyone with more than a passing interest in the game. (Review)
Best Free Billiards and Pool Game
BillardGL , a brilliantly crafted open-sourced freeware game that affords play of either 8-Ball or 9-Ball. The 3D graphics are second-to-none and the physics appear to be flawless.
The user interface is simple and the controls straightforward. As you assess your next shot, you can view the table layout from any perspective you want, roaming and zooming and peering. (Review)
Best Free Breakout Game
LBreakout2 , an extremely polished Breakout Clone features a two-player mode (local or over the internet or LAN), fine animations and graphics, excellent controls, the ability to save a game, a level editor, and a turbo key.
This game gets regular Level Set updates. The fun continues well beyond when you have mastered the 50+ levels. (Review)
Best Free Computer Chess
PyChess , with this program, you can play against the GNU Chess engine or lots of other chess engines, such as the Crafty engine. You can also play Internet chess by connecting to the FICS servers.
It allows for saving games in the PGN, EPD and FEN chess file formats so that you can always return to continue with the games or analyze them. It also offers opening books and other useful features including undo moves, hint and spy modes, sound and animation effects." (Review)
HOXChess , a well designed open source Chinese Chess application with highly configurable user interface and multi engines for you to choose from. You can also easily connect to multi remote Xiangqi servers to play the game online. (Review)
Best Free Computer Go
Best Free First-Person Shooter
Urban Terror , described as fun over realism by the creators, the game has fast paced, intense game-play. Urban Terror doesn't throw realism to the wind mind you, but rather tries to enhance game-play with elements like powerslides and wallhops.
Five different game types, over a thousand servers, plenty of players to go around and no waiting for people to show up. (Review)
Best Free Hearts Game
Best Free Jigsaw Puzzle
Best Free Lemmings Game
Pingus , play a free clone of the popular Lemmings game and guide as many penguins as possible to build bridges, climb, bash and use their talents to reach home before they fall into traps. Optional sound effects and music, plenty of level sets and even a level editor are available for challenging your skills.
Best Free Match-3 Puzzle
Frozen Bubble , designed with colorful 3D rendered penguin animations and 15 stereo sound effects, Frozen Bubble comes with editable 100 levels for 1-player game, or hours and hours of 2-player game. You can also choose to have multi-player game over the local area network or Internet.
Play this game with the left or right key to aim your shot and up key to fire. Hone your skills in speed and accuracy before the bubbles get frozen! (Review)
Best Free Physics Game
Numpty Physics , an excellent open source and multi-platform physics game with 35 built-in levels. It has more to offer than the free prototype of Crayon Physics Deluxe.
You're able to draw custom shapes and have access to all levels at once, so you don't have to worry if you get stuck at a level. The sketches look more like what a 3-year old has drawn and don't have the professional feel of Crayon Physics. But who cares? I'm also not an artist! (Review)
Best Free Pipe-Building Puzzle
PipeWalker , solve this casual puzzle in building a piping or network system by connecting all scattered pieces with your logic and skill. With support for four map sizes, themes and auto save, it has multiple levels for you to figure out.
Best Free Reversi
Best Free Sandbox Game
Dwarf Fortress is so horrendously in depth. It's nearing insanity, everything from the dynamic flow of water in the moats to several dozen types of ore, gems and utility stones by the book. You can spend anything from minutes to hours playing this 'uber' creative game.
Best Free Simulation Game
OpenCity , a 3D city simulator like a classic SimCity game for you to construct a city divided into residential, commercial and industrial zones. You can connect them by building roads, provide the city with necessary goods and watch it grow up with the power you supply.
TORCS (The Open Racing Car Simulator) , a multi-platform car racing simulation game allows you to drive different cars in races against computer opponents or human players. The game play allows different types of races from a simple practice session up to the championship while the simulation features a simple damage model, collisions, tire and wheel properties, aerodynamics and more. (Review)
Best Free Sudoku Puzzle, Generator and Solver
HoDoKu , an open source program allows you to generate sudoku puzzles in five different and configurable difficulty levels. It also includes a solver and an analyzer to help you solve the puzzles.
While playing the game, you can select to view a summary of solving techniques and solution paths. When you click on a solution path, it highlights the steps on the corresponding grid to help you analyze the game. (Review)