REBEL 11.0 review
by Joe Petrolito
Chess players are becoming increasingly spoilt when it comes to software. The last few years
have seen enormous improvements in the Rebel line, and the latest version provides an extensive
range of tools for players of all strengths. A few years ago, Rebel was provided on several
floppy disks (I still have them!). Today, this is not only impractical (I don't fancy inserting
several hundred floppy disks), but also unthinkable given the sheer amount of material provided.
The latest version is a significant improvement over the previous version, and consists of two
separate products, namely Rebel Century 3 and Rebel Tiger II. The latter is a combination of
the Chess Partner interface, two Chess Tiger engines and a Lokasoft engine. I will discuss the
products separately below, although I won't discuss the basic features that no current-day
program would be without, such as playing levels, display options, and so on. It's sufficient
to say that there are plenty of these features, and they should satisfy most users. Extensive
details on each product can be found on the Rebel web site. The package comes with a brief
printed manual that describes the installation process. On-line manuals and help are also
available for the individual programs.
Rebel Century 3
Rebel Century 3 is a DOS-based program, although it will also run under Windows. A pure
Windows-based version was mooted last year, but this has happened yet. The program is operated
via an extensive menu system and on-screen shortcuts. The screen layout is completely
configurable and the program comes with a set of different layouts. Users can change the layout
to suit their requirements, and these new layouts can be saved.
The package includes five engines, namely Century 3 and the Rebel 7, 8, 9 and Decade engines.
Century is the strongest engine, with the others being progressively weaker. The relative
strengths of the engines can be compared by running automatic computer-computer matches.
Rebel engines have always been noted for their human-like play, and the new version is doing
very well against humans, including winning the recent Debrecen tournament. Clearly, Century is
too strong for all but the top players. For those of us who are not of GM strength, it's
possible to weaken the engines in various ways. The way I like to do this is by setting an ELO
rating for the strength.
Century's style can be varied in two ways. Firstly, the user can select one of five styles
ranging from "aggressive" to "defensive". Secondly, the style of play can be changed by
adjusting various search options. Some pre-configured styles for famous players are included,
and others that were developed by beta-testers and end-users are on the web site. This of
course leads to the question as to what the strongest settings are. It's difficult to answer
this question without very extensive testing, but clearly there is a lot of scope for
experimentation if you are interested.
Opening books and related tools
The chess engines are supported by a huge opening book with 2.6 million positions, and further
specialized books are included on the CD. A separate chess tree is provided by the Encyclopedia
of Chess (EOC), which was introduced in Rebel 10. It is basically a tree of 20 million chess
positions that includes win/loss statistics for each position. Further details on EOC are
given in my review.
A utility is provided for generating EOCs from any database of games. Two other trees also
complement the opening book, namely a one-million Computer Analysis Project (CAP) tree from
Dan Corbitt's team and a Computer Analysis Tree (CAT). The CAT concentrates on computer-computer
games and analysis from computer programs. All three trees can be used to influence Century's
decision-making in the opening.
The analysis options in Century are extensive, and include continuous analysis as you play
through a game, and full analysis of individual games or set of games and problems. The analysis
can be controlled by specifying moves to be either included or excluded. Statistics and ELO
ratings are automatically generated for standard test sets that are provided with the program.
Database and search features
The database has been expanded to around 800,000 games, which is stored in Rebel's own format.
Century also supports PGN directly, and tools are provided to convert database in Chessbase cbf
format and Nicbase formats. The search options have quite extensive, and are starting to rival
those provided by dedicated database programs. Searches can include header information (names,
dates, etc.), positions, and material or material patterns. Options can be combined using a
search mask, with any option being able to be either included or excluded.
Rebel Tiger II
Rebel Tiger II is a windows-based program that acts as an interface to the Tiger chess engines
and winboard-based engines, and as an interface to internet chess servers. A Century 2 engine
is provided for analysis to complement the Tiger engines. As a chess-program interface, it
offers a range of features that are similar to Century, so I won't discuss these. The main
differences between Century and Tiger are:
The program is operated via a standard windows interface, and is very simple to use and highly
- (a) Century provides more extensive search facilities,
- (b) Tiger can be used with the numerous (and free!) winboard engines such as Crafty, and
- (c) the database formats are different. Tiger handles games stored in ChessPartner, cbf or PGN
formats, and positions in EPD format.
The internet console offers a complete and comfortable link to telnet-based chess servers such
as ICC and FICS. Preconfigured sessions are provided, and new or modified ones can be quickly
created and saved for future use. Users can log in as a human or a computer. In computer-mode,
the chess engine plays without any human intervention during the game. It's possible to have
the engine automatically seek matches, and in this way the engine can be playing all the time.
Games can be automatically saved to a database in both modes of operation.
Two versions of Tiger are included, namely the standard Tiger 13, and the new Tiger Gambit.
Tiger is a very strong engine, and a previous version topped the SSDF list. The latest versions
are also performing very well, with Gambit winning the recent computer Dutch Open. Gambit caused
a lot of interest amongst the beta-testers, and I must admit I spend most of my time testing
this version of Tiger.
Gambit has an exceptionally aggressive style that makes it a pleasure to watch its games. It
loves to conduct a mating attack whenever possible, and this often results in speculative play.
This style of play is very difficult for humans to counteract, as Gambit's numerous internet
opponents quickly found out. So, although the standard version of Tiger is probably slightly
stronger, the Gambit version is more fun. Take your pick!
Rebel 11 offers a fine collection of chess software at a great price. The different programs
complement each other nicely, and cover many of the things chess software is used for. Given
this, it is very easy for me to highly recommend it.