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Sigma Chess 6.2

Free Mac OS X Chess Software

Sigma GameWare
Ole K. Christensen

Sigma Chess is a freeware, master strength Macintosh chess program for Mac OS X. The feature set includes: Optional HIARCS engine, UCI Engine support, Databases, PGN/EPD, basic desktop publishing, endgame databases, novice levels, a true perspective 3D board, ExaChess compatibility and much more. Sigma also runs on Classic Mac OS, but this is no longer officially supported.

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Site last updated: August 26, 2012
Latest software version: 6.2.1

2012-11-11 Sigma Chess Open Source Project
2012-08-26 HIARCS Chess Explorer Released for Mac OS X NEW
2011-07-21 Sigma Chess & Mac OS X 10.7 (Lion)
2011-03-13 Sigma Chess 6.2.1 with HIARCS 13.2 and Deep Junior 12
2011-03-11 New award from
2009-11-17 New Grand Master library available for download

About Sigma Chess

Welcome to the Sigma Chess home page! If you own a Macintosh and you like chess, you should download Sigma Chess. You can:

Play chess against the strong built-in engine: Adjust the playing strength to your own level simply by setting the ELO rating for Sigma Chess, and choose among the many playing modes, levels and styles.
Play chess against the World Chess Championship strength HIARCS 13 and Deep Junior 12 engines bundled with Sigma Chess: Sigma Chess supports the UCI (Universal Chess Interface) protocol, so you can use other UCI chess engines for Mac OS X. Click here for a list.
Analyze and annotate games: Instruct Sigma Chess to annotate games with its analysis, or add your own free text annotations including diagrams and move suffixes. You can even write and print your own chess literature.
Maintain & access game collections/databases: The built-in database manager lets you filter and sort large game collections. Additionally you can import PGN game files that you have e.g. downloaded from the internet (see the Selected Chess Links). Sigma Chess can also be used as an engine from within ExaChess.
Customize the appearance & behavior of Sigma Chess: You can choose among the various piece sets, board types, types of move notation, colour schemes, the true perspective 3D board etc.

Sigma Chess Lite & Pro

As of version 6.2, Sigma Chess is only released as FREEWARE including the full feature set of the previous Pro version.

Sigma Chess & Mac OS X 10.7

Sigma Chess does unfortunately NOT run on the new Mac OS X 10.7 (Lion).

As of Mac OS X 10.7 (Lion), support for legacy PowerPC applications such as Sigma Chess has been discontinued.

Sigma Chess is such a legacy PowerPC application using the Carbon APIs, and the built-in engine is written mainly in PowerPC assembler. Therefore producing an Intel version (and switching to the Cocoa APIs) will more or less require a complete rewrite. Chess programming is just a hobby, and my spare time is limited, so I alas won't have time to move away from the legacy PowerPC/Carbon platform.

Fortunately, Mark Uniacke, author of Hiarcs, has now released a brand new Mac OS X chess product - HIARCS Chess Explorer - which includes the World Chess Software Champion HIARCS 14.

I apologize for the inconvience this is causing, but it's time for me (and Mac OS X) to move on. I would like to thank all of you for your feedback and support over the past 10 years.


Sigma Chess Open Source

Sigma Chess has been released as Open Source through Google Project Hosting under a BSD license

The purpose of this Open Source project is to port Sigma to Cocoa/Intel. Let me know if you want to sign up. But please note that I will not be taking actively part in this project.

The Author

Sigma Chess 6.2 is developed by Ole K. Christensen. If you have any questions or comments please check out the FAQ or send me an e-mail.

Copyright (C) 2012, Ole K. Christensen