Free Kriegspiel Revival
Free Kriegspiel Revival (FKR) is the movement to revitalise ideas of roleplaying that existed prior to the publication of Dungeons and Dragons that were descended from free kreigspeil or umpired wargaming.
The key examples of these games are the Braunstein umpired wargames (which were a lot like proto Matrix Wargames) and the early Tekumel games.
These games often focus on the free flowing narrative between the players and the umpire with the umpire resolving mechanics (if there are any) and communicating the results narratively rather than mechanically.