Surprise - A WinBoard Chess Engine

(Last update: 19-Oct-2007)

This page presents the WinBoard chess engine "Surprise". It is a free, non-commercial, amateur engine playing chess - nothing more. There is no warranty that it works as expected. Downloading and installing it is at your own risk.

The playing strength of Surprise-4.2.8 is about 1900 (WBEC: 1869 after edition 14). For version 4.3-beta13 there is no rating available yet.

Download the current version Released: 19-Oct-2007
(fast windows build by Jim Ablett, strongly recommended!) Released: 19-Oct-2007

Change log

Changes in 4.3-beta13 against 4.3-beta11:

Changes in 4.3-beta11 against 4.3-beta1:

Changes in 4.3-beta1 against 4.2.8:

Unfortunately I am not able to look at the code diffs anymore. This is because I had lost all my original sources of the 4.2.8 release (and also of several older releases) after some "data accident" on my hard disk in 2006. I was able to recover large parts of my recent sources and could continue my work but at that time I had already made many changes to the original 4.2.8 version.

I could try to summarize what I did, but this time I think it is not worth the effort because I would mix up things that already happened in 4.2.8 with newer changes. Most of my changes were one of these:

Changes in 4.2.8 against 4.2.7:

Changes in 4.2.7 against 4.2.6:

Changes in 4.2.6 against 4.2.5:

Changes in 4.2.5 against 4.2.4:

Changes in 4.2.4 against 4.2.3:

Changes in 4.2.3 against 4.2.2:

Changes in 4.2.2 against 4.2.1:

Changes in 4.2.1 against 4.2:

Changes in 4.2 against 4.1.6:

Changes in 4.1.6 against 4.1.5:

Changes in 4.1.5 against 4.1.4:

Recommended settings:
When playing against another engine on a single-processor machine, you should set ponder=OFF in most cases (note that pondering is not yet implemented in "Surprise").
Beginning with Surprise-4.1.3, a main hash table is used with an internal default size of 64 MB. This value can be changed via config file "surprise.ini".
Endgame tablebases are not yet supported.

Unzip the archive to any directory you like. Surprise looks for the opening book in the current working directory from where you run the program.

Download older versions Released: 17-Oct-2007 Released: 24-Jul-2007 Released: 23-Jul-2006 Released: 14-Jan-2006 Released: 4-Oct-2005 Released: 24-Sep-2005 Released: 5-Sep-2005 Released: 20-Aug-2005 Released: 13-Apr-2005 Released: 21-Dec-2004 Released: 22-Nov-2004 Released: 19-Sep-2004 Released: 15-Aug-2004 Released: 26-Jul-2004 Released: 9-Jul-2004 Released: 22-Jun-2004 (**) Released: 20-Jun-2004 (**) Released: 13-Jun-2004 (**)

Please note: older versions marked with (**) may have had some time management problems, especially in incremental mode!

Source code

Up to now I did not decide whether the source code will be publicly available.

About the engine

What's still missing:

About the author and the engine's history

Sven Schüle, born on 11-Mar-1965, living in Berlin (Germany). Studied computer science, now working as a freelancer in software development projects. Playing chess in a club since 1981, current national rating about 1870 ("DWZ"). First chess programming activities started in 1986 together with my friend Frank Sek. Later on I wrote some private chess programs on an Atari ST and then on a Win95 PC. The first version of "Surprise" was created about 1991 on Atari. Versions 3.x (still private, developed in 2000/2001) were the first versions playing at least acceptable chess. After 3 years break, I continued development in 2004.

Contact: Sven dot Schuele at gmx dot de