The standard proprietary format for ChessBase and Fritz GUIs.
, performance percentages, and the specific years moves were played. Hand-Tuned Precision
When searching for the HIARCS 15q book, you will almost certainly encounter the term "repack" in descriptions.
Unlike automated books that blindly scrape millions of low-quality online blitz games, the HIARCS 15Q book is hand-curated and heavily filtered. It contains millions of positions meticulously evaluated by grandmasters and top-tier engines. It provides deep, statistically verified variations that steer your engine away from tactical traps and toward positionally sound, deeply researched middlegames. Key Components: Understanding CTG Formats and Repacks
: On average, the tournament book contributes an improvement of about 40 Elo points per year chess hiarcs 15q openings book includes ctg and repack
: Native formats for HIARCS Chess Explorer (Pro) on both Windows and macOS. Key Content Features
The .ctg format is not used by the engine itself (HIARCS) but rather by the graphical user interface (GUI) that manages the engine. This is a crucial distinction: the GUI uses the CTG book to tell the engine which move to play in the opening, allowing the engine to save its computational power for the middlegame and endgame.
Furthermore, a repack might not be the complete experience. The most advanced official books, such as the "GM+ in Deep HCE Pro," contain over 18 million positions drawn from both over-the-board and correspondence games and are accessed through , an experience a static repack cannot replicate.
| Opening Book Name | Based On | Number of Positions | Typical Access | Format | | :--- | :--- | :--- | :--- | :--- | | | Top GM & Correspondence Games | 18,056,747 | Online (Deep HCE Pro) | FHBS | | Human Reference | All Known Human Games | Up to 54.7 Million | Local/Online | HBS/FHBS | | Tournament CTG Book | Top Quality (GM & Engine) | ~33.6 Million (as of Apr '26) | Local | CTG, HCS | | HIARCS 15s (Engine) | Strong Human & Computer | 15,422,195 (Moves only) | Local (HCE Pro) | HCS | | Local Book (HCE) | GM Over-the-board | ~1.1 Million (Standard HCE) | Local (Included) | HBS | The standard proprietary format for ChessBase and Fritz GUIs
: It removes the tedious steps of manual directory mapping.
You can use a CTG book to guide Fritz or ChessBase engines during infinite analysis or engine tournaments.
Assuming you have obtained the package that , follow this step-by-step guide:
Good repacks pre-configure the directory paths. You won’t have to manually move .ctg , .ctb , and .cto files into specific ChessBase folders; the installer handles it. Unlike automated books that blindly scrape millions of
The phrase "includes CTG" is a major feature for experienced users. CTG, which stands for , is the proprietary opening book format used by the ChessBase family of software (including Fritz). While the CTG format is not open source, a partial specification has been documented.
For professionals and enthusiasts looking for the pinnacle of engine-compatible opening books, the provides a definitive, high-performance solution.
This is a of the commercial chess software Hiarcs 15q , specifically focused on its opening book functionality.