Wargames & other Historical simulations
Military historians have long studied war. The first war'game' was probably the one designed by Georg von Reisswitz, that so impressed the Prussian army in 1824 that they used it for training their officers. They would submit written orders to an umpire - usually Georg himself - who would then move scale models made of lead around an accurately mapped out battlefield. By 1828 there were recreational clubs playing this Kriegspiel, but it wasn't until the Franco Prussian war (that the Prussians decisively won by capturing Paris) that the rest of the world caught on. And in many ways it even then took until HG Wells published Little Wars in 1913 for a wargame to be a product a person could buy.
And then in 1954 people put a wargame in a box with counters and a board, and sold it under the name Tactics. It was a runaway success. Some of the greatest names in our industry got their first start writing hex and chit based wargames - Lou Zocci, Gary Gygax, companies like SPI and Avalon Hill. There was a time when this WAS the hobby, when games like D&D were a weird little offshoot, and Catan hadn't received its first settler.
Modern wargames are more accurately modern 'historical simulation games'. Its not just battles and armies - it can be diplomacy, tactics, politics, strategy. But it still strives to do what Georg von Reisswitz pioneered almost two hundred years ago - to accurately model real historical situations, replay them so we can learn from them.