The game of chess has challenged and entertained players for centuries. From the courts of medieval royalty to modern after-school chess programs, the game has widespread appeal and has withstood the test of time. Chess is easy to learn but difficult to master. Each player controls 16 pieces on a board consisting of 64 squares. There are six different types of pieces: Pawn, Bishop, Knight, Rook, Queen, and King—so learning the basics can take an hour or so.
However, learning the basics is just the beginning. It takes time and practice to master the skills to handle the many possible variations in a game. Mathematician Claude Shannon calculated that there are 1043 possible legal moves in a chess game.
Like many classic games, chess is available as a computer application for almost every computing platform, including smartphones. This roundup includes seven different open source Android applications that chess enthusiasts should check out. With these apps you can play chess against your phone or an online opponent, study and analyze chess games, turn your phone into a basic chess clock, and even organize a chess tournament. All of these apps are in the F-Droid repository, which is an excellent resource for users who want to avoid the Google Play store, and only use purely open source software on their Android device.
Despite being simply named, Chess is the app on this list with the most features. The standard play mode includes features such playing in blind mode with the pieces hidden, and supports Chess 960-Fisher Random mode, which changes the starting locations of the pieces. In addition to play vs. computer, play vs. another person locally, and online play, Chess includes a puzzle mode and a practice mode. The puzzle mode challenges players with "Mate in Two" exercises, while the practice mode races the player against the clock. Users can download practice sets, a beginner puzzle set, and other add-ons from the Chess website. The version of the app in F-Droid has not been updated since 2014, but it is a mature, polished app. It is available under an MIT license, and source code is on GitHub.
Chess Walk is a simple, basic chess program. Players compete against a computer opponent, or against an online opponent via the Free Internet Chess Server. Beyond that, Chess Walk offers few extra features, and while it might not do as much as some of the other chess programs on this list, it is the perfect choice for a user looking for an lightweight app that does one thing and does it well. Chess Walk's source code is hosted on GitLab, and the app is licensed under the GPLv3.
DroidFish is built on the Cuckoochess and StockFish chess engines. It supports a wide variety of game modes, including two players playing on the same device, and two computer players playing each other. The app supports opening books and endgame tables, displays arrows showing possible moves, and has an analysis mode and a blind play mode. If Scid on the go (see below) is installed, DroidFish can read the Scid files, allowing the user to review chess games inside DroidFish. With so many features aimed at helping users study and improve their chess game, DroidFish is an excellent choice for a user wanting an app for digging deep into strategy.
DroidFish is licensed under the GPLv3. See developer Peter Österlund's page for links to the source code and build instructions.
Scid on the go
Scid on the go is a mobile viewer for Shane's Chess Information Database files. These files are collections of chess games for study and review. The version of Scid on the go in F-Droid has not been updated since 2013, but the version in the Google Play Store has a version that was updated in May of 2015. Despite the fact that the F-Droid version is somewhat outdated, it can fetch and import files from The Week in Chess magazine with no problems, but it does seem to have issues connecting to ChessOK. Released under the GPLv2, Scid on the go's source code is hosted on Google Code, and there does not seem to be a more up-to-date repository.
ChessWatch is one of the two chess clock applications available in F-Droid. It turns an Android device into a impromptu chess clock, but it is not as nice as using a real chess clock. Use it to set the initial time on the clock, and the amount of time added to each player's time after each move. The clock uses the Fischer delay method for adding time to the clock. The button for ending a turn is very small, and most of the screen is just wasted space. ChessWatch's source code is available on GitHub, and the project uses the GPLv2.
Simple Chess Clock
The other chess clock available in F-Droid, Simple Chess Clock, is a little more robust than ChessWatch. Simple Chess Clock supports setting the initial start time and delay time. It can also supports three different delay methods: none, Bronstein, or Fisher. The buttons for each player are much larger than ChessWatch's, and are located at the edge of the screen, making it a little easier to use. Simple Chess Clock is released under GPLv3, with source code on GitHub.
Swiss Chess Tournament
Playing against a computer or an online opponent is a rewarding experience, but it is not as exciting as playing a real person, face-to-face. Swiss Chess Tournament is a simple app for setting up a Swiss-system tournament. In a Swiss tournament, players play against opponents with similar rankings in each round without having repeat matches. While the app would benefit from some usability enhancements, this Apache2-licensed application is good enough for setting up a basic chess tournament for smaller groups. Swiss Chess Tournament's source code is on GitHub.