Details about the unit (for instance, its identity as well as its attack, defense and movement scores) can then be seen easily by the owning player, while the opposing player will be left unsure of the exact nature of piece; while he can see where his rival's forces are, the fog of war is emulated by preserving the secrecy of the type and quality of the troops.
The initial idea of pieces that are visible to only one of two players traces back to the 1908 introduction of the game L'Attaque, the first version of Stratego.
In 1972, Lance Gutteridge of Gamma Two Games originally planned on using six-sided dice to represent pieces and to provide for step reduction in combat strength.
The high cost of dice led him to decide to instead use embossed wooden blocks showing 2, 3 or 4 steps in combat strength.
GMT Games entered the block wargame market in 2003 with the release of Europe Engulfed, a simulation of the entire ETO.
GMT also released a block wargame series called Commands and Colors: Ancients which met with wide approval.
Since 2011, VentoNuovo Games has modernized the block wargames sector with the use of new logical algorithms and the creation of ultra-detailed topographic maps.