Chess Opening Databases
The Opening Databases organize all 3,815 chess openings in the MasterInChess Openings System (MICOS) into the 5 Main Groups and 57 Opening Groups. Every opening is classified by its opening name, chess notation and unique MICOS code, making it easy to find, compare and explore related opening systems.
Each Opening Group contains a complete database of its recognized openings. Whether you are studying a new opening, comparing variations or looking up a specific position, the database provides a structured way to navigate the entire MICOS opening classification.
Every opening can be explored directly in MICOS CAP, where you can replay the opening move by move, analyse the position, build your own opening repertoire with multiple variations and save it as a PGN file to continue your work later.
Choose a Main Group below to begin exploring the MICOS Opening Databases.
Flank Openings
MICOS Opening Groups A00.IO to A04.RE
Flank Openings are characterized by White beginning the game with moves on the wings (flanks) of the board, such as 1.Nf3, 1.c4, or 1.g3, instead of the central pawn advances 1.e4 or 1.d4.
In MICOS, Flank Openings offer a flexible and modern approach to the opening phase, emphasizing strategic maneuvering, delayed central control, and adaptability to various opponent responses.
The Flank Openings group includes major systems like Irregular Openings, the Reti Opening, the English Opening and the Bird’s Opening — all openings that blend classical development principles with cutting-edge strategic ideas.
Flank Openings often transpose into other systems or lead to unique independent structures, giving players rich possibilities to outmaneuver their opponents from the earliest moves.
King’s Defences
MICOS Opening Groups B00.IK to B09.AL
King’s Defences arise when Black immediately counters White’s 1.e4 move with flexible defences that aim to sidestep classical e5 central play.
In MICOS, King’s Defences showcase a wide array of modern and hypermodern defences such as the Pirc, Caro-Kann, Alekhine’s Defence and the Sicilian Defence.
These systems prioritize dynamic piece play, counterattacks, and flexible pawn structures rather than rigid symmetry.
King’s Defences are a battleground where initiative, creativity, and precise calculation are critical — providing players with numerous ways to fight for equality or even early advantage with Black.
Open Games
MICOS Opening Groups C00.KP to C17.RU
Open Games occur after 1.e4 e5, where both players occupy the center early, leading to open files, rapid development, and sharp tactical possibilities.
In MICOS, the Open Games group covers famous classical systems like the Italian Game, Scotch Game, King’s Gambit, Vienna Game, and the legendary Ruy Lopez Opening.
Open Games are prized for their clarity of plans, early imbalances, and rich tactical motifs — making them ideal both for deep strategic learning and spectacular attacking chess.
Closed Games
MICOS Opening Groups D00.QP to D06.SE
Closed Games arise primarily after 1.d4 d5, leading to slower, more strategic battles where pawn structures and maneuvering dominate over immediate tactics.
In MICOS, the Closed Games group includes foundational systems such as the Queen’s Gambit, the Tarrasch Defence, the Semi-Slav and various other classical Queen’s Pawn Games.
These openings teach deep positional understanding, pawn breaks, and long-term planning — crucial skills for players seeking to master the subtler dimensions of chess.
Queen’s Defences
MICOS Opening Groups E00.IQ to E16.GR
Queen’s Defences describe hypermodern or flexible responses to 1.d4, where Black seeks to contest White’s center indirectly rather than occupying it immediately.
In MICOS, Queen’s Defences include major defences like the King’s Indian, Grunfeld, Nimzo-Indian, Queen’s Indian, Dutch Defence and many more powerful systems.
These defences often lead to complex pawn structures, dynamic piece play, and long-term strategic struggles — a true test of modern chess mastery.
The MICOS system organizes Queen’s Defences into accessible, structured groups that allow both players and instructors to deeply understand their strategic foundations and critical move orders.