Sigma Chess 6.2 is now freeware only and includes all the features from the previous Pro version.

Now bundled with the new HIARCS 13.1 engine! This engine is a Universal Binary and thus runs at full speed on Intel Macs. Additionally, a multi processor version is available for even stronger play.

A buffer overload bug has been fixed in the UCI Loader.

Now bundled with the new HIARCS 12 engine! This engine is a Universal Binary and thus runs at full speed on Intel Macs. Additionally, a multi processor version is available for even stronger play.

Sigma Chess 6.1.5 includes the following improvements and bug fixes:

• Now bundled with the new HIARCS 11.2 engine! This engine is a Universal Binary and thus runs at full speed on Intel Macs. Additionally, a multi processor version is available for even stronger play.

• No longer crashes when opening Sigma by double clicking a previously saved game or collection.

• No longer fails when importing long PGN games.

• The Copy Analysis function now copies all lines in case MultiPV is used.

• Fixed a bug where Analyze Game sometimes skipped moves.

• Improved the time allocation handling in the low ELO settings.

Note for OS 9 Users: The HIARCS engine and other UCI engines are only available on OS X. However, you can still use Sigma's built-in engine.

Note for owners of previous versions of Sigma Chess 6.x Pro: Sigma Chess 6.1.5 is a FREE upgrade, and will automatically run in Pro mode if Sigma Chess 6.1.4 Pro is currently installed. For earlier versions of Sigma you will need to enter your license key again.