PBEM

Play-by-mail games, or play-by-post games, are games, of any type, played through postal mail or email.

Correspondence chess has been played by mail for centuries. The boardgame Diplomacy has been played by mail since the 1960s, starting with a printed newsletter (a fanzine) written by John Boardman. More complex games, moderated entirely or partially by computer programs, were pioneered by Rick Loomis of Flying Buffalo in 1970. The first such game offered via major e-mail services was WebWar II (based on Starweb and licensed from Flying Buffalo) from Neolithic Enterprises who accepted e-mail turns from all of the major e-mail services including CompuServe in 1983.

Play by mail games are often referred to as PBM games, and play by email is sometimes abbreviated PBeM—as opposed to face to face (FTF) or over the board (OTB) games which are played in person. Another variation on the name is Play-by-Internet (PBI) or Play-by-Web (PBW). In all of these examples, player instructions can be either executed by a human moderator, a computer program, or a combination of the two.

In the 1980s, play-by-mail games reached their peak of popularity with the advent of Gaming Universal, Paper Mayhem and Flagship magazine, the first professional magazines devoted to play-by-mail games. (An earlier fanzine, Nuts & Bolts of PBM, was the first publication to exclusively cover the hobby.) Bob McLain, the publisher and editor of Gaming Universal, further popularized the hobby by writing articles that appeared in many of the leading mainstream gaming magazines of the time. Flagship later bought overseas right to Gaming Universal, making it the leading magazine in the field. Flagship magazine was founded by Chris Harvey and Nick Palmer. The magazine still exists, under a new editor, but health concerns have led to worries over the publication's long term viability.

...
Wikipedia