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an UCI-compatible open source chess engine developed by Tord Romstad under the GPL 3. Glaurung is the forerunner of Stockfish by Marco Costalba, Joona Kiiski and Tord Romstad, as well the Apple iPhone program powered by Stockfish, incorporating the Glaurung GUI. The companion program GlaurungServer allows to run the chess engine remotely on a home computer [1]. Glaurung, first released in fall 2004, is written in C, later versions completely in C++. It is portable and able to run on Windows, Linux, Mac OS X and mobile platforms.

Chess960 compliant, Glaurung played two Livingston Chess960 Computer World Championships, in 2005 where it became third, and the in 2006. It won two times the International Open Polish Computer Chess Championships, in 2007 [2] and 2008, and further played the ICT 2007, and the CCT8, CCT10, and CCT11 online tournaments.
Glaurung by John Howe [3] [4]


Board Representation

Glaurung versions prior to 2.0 applied 16x16 Vector Attacks [5] [6], combining the property of the 10x12 board with its surrounding ranks and files, which ensure a knight can not jump off the board, with the property that a square difference uniquely maps a vector in the Chebyshev vector space of a chessboard. With the advent of Magic Bitboards, Glaurung 2 was a complete rewrite [7] utilizing bitboards as primary board representation.


Glaurung is a PVS searcher [8], using advanced selectivity, and was beside Fruit the program which made LMR popular [9] . Since early 2006 Glaurung 1.x supports SMP search.


Glaurung's evaluation is tellingly summarized by Tord's evaluation philosophy, covering orthogonality, continuity, sense of progress and good worst case behavior [10]. Glaurung applies a tapered evaluation to make a smooth transition between the game phases.

Gaurung GUI

In 2007, Tord released an own UCI compliant GUI for Mac OS X, written in Objective-C using the GNUstep [11] implementation of the Cocoa Widget toolkit [12], later ported for the iPhone.
Glaurung with own GUI for Apple iPhone [13]

Play Magnus

In February 2014, a modified and tuned version of Glaurung became the chess engine of Play Magnus [14], a chess application for iPhone and iPod Touch by Play Magnus AS, an Oslo, Norway-based company founded by Magnus Carlsen [15], who became World Chess Champion in November 2013.

See also

Forum Posts







2010 ...

External Links

Chess Engine



  1. ^ Glaurung
  2. ^ Glaurung is new Polish Champion by Werner Schüle, CCC, July 01, 2007
  3. ^ Glaurung - Middle-Earth Encyclopedia
  4. ^ Glaurung slain by Túrin Turambar, Glaurung - Lord of the Rings Wiki
  5. ^ Re: Fruit's Board Representation? by Tord Romstad, Winboard Forum, April 27, 2005
  6. ^ Re: 0x88 engines by Tord Romstad, CCC, May 05, 2009
  7. ^ Glaurung 2-epsilon by Tord Romstad, CCC, May 06, 2007
  8. ^ Re: What's the difference between Glaurung and Gothmog? by Tord Romstad, CCC, March 02, 2005
  9. ^ An Introduction to Late Move Reductions by Tord Romstad
  10. ^ The Art of Evaluation by Tord Romstad, CCC, August 2, 2007
  11. ^ Writing portable code - GNUstepWiki
  12. ^ Glaurung GUI for Mac OS X (and possibly Linux) by Tord Romstad, CCC, July 03, 2007
  13. ^ Glaurung
  14. ^ Re: Play Magnus: official App with Chess Engine by Tord Romstad, CCC, February 26, 2014
  15. ^ Play Magnus
  16. ^ Glaurungchess site by Günther Simon, CCC, May 10, 2016

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