All game elements are interactive, allowing players to explore, roleplay and interact with non-player characters (including monsters) and other player characters, gameplay combat on various scales, and improve their position over time.

Turnaround time is how long a player has to prepare and submit "orders" (moves and changes to make in the game) and the company has to process them and send back turn results.

[4] The company processes the turns and returns the results to the player, who completes a subsequent order sheet.

[11] The initial choice of a PBM game requires consideration as there is a wide array of possible roles to play, from pirates to space characters to "previously unknown creatures".

[16][e] Chris Harvey started commercial PBM play afterward in the United Kingdom with a company called ICBM through an agreement with Loomis and Flying Buffalo.

[17] ICBM, followed by KJC games and Mitregames, led the UK PBM industry.

[18] For approximately five years, Flying Buffalo was the single dominant company in the US PBM industry until Schubel & Son entered the field in about 1976 with the human-moderated The Tribes of Crane.

[20] In 1981, some PBM players launched another company, Adventures by Mail, with the "immensely popular" Beyond the Stellar Empire.

[16][f] The proliferation of PBM companies in the 1980s supported the publication of a number of newsletters from individual play-by-mail companies as well as independent publications which focused solely on the play-by-mail gaming industry such as the relatively short-lived The Nuts & Bolts of PBM and Gaming Universal.

The PBM genre's two preeminent magazines of the period were Flagship and Paper Mayhem.

[25] Landes made significant changes from the playtest, and designed most of the game between March 1988 and May 1989, to include creating the first module Crown of Avalon.

[26] The original game system, Legends I (LI), operated by paper copy and postal mail.

[37] As of 2013, players interact through an application which provides "graphical displays, data-driven dashboards, and order-writing tools" to enhance the game.

[42] No combat was allowed in the first turns to help confirm smooth game operation and prevent early player knockouts.

[44] The publisher randomized characters and locations to prevent players in multiple games from gaining an advantage.

[47] In 1994, the editors of Flagship magazine stated that this module was "an almost pure power game".

[22] The Dark Domain module offered "a good mix of role-playing and wargaming, where teamwork and communication [were] necessary for success".

[49] The designers noted this game would suit all types of players, including those with "lone wolf and small positions".

[50] Story line, roleplaying, and questing were elevated in importance, allowing easier advancement.

[52] As of 2022, Harlequin Games offered multiple game modules: Adventures in Avalon, Blood Tides Rising, Crown of Chaos, Immortal's Realm, Jade Eye, North Island Campaign, Swords of Pelarn, The One Ring, and Twilight Crusade.

[31] Turns are processed by computer, although in early versions certain special actions could be hand moderated.

Besides the basic name and sex, these include an insignia, race, culture, characteristics and attributes, spells (over 400 available), equipment, and others.

[60] Forces comprise groups of characters such as Legions or Fleets, but also physical locations such as Castles and Towns as well as Lairs and Ruins.

[60] Thematic options in the modern game range from "a warlord ruling a great empire, to a heroic adventurer, to a wandering bard and dreamer".

[63] The martial aspects of play are customizable, including design of forces and method of employment.

[64] A Legends playtester presented a positive view of the early game with his statement that it "stuns the imagination!

"[25] David Dyche reviewed Legends in a 1990 issue of Paper Mayhem magazine noting, "The program is enormous, the routines powerful, and the depth of the game amazing.

"[1] Dave Chappell reviewed Legends in the May–June 1995 issue of Flagship stating "After five years of play I am still not tired.

"[33] In a 2002 issue of Flagship magazine, the editors stated that Legends had "breath-taking materials, varied modules, and a huge range of opportunities for different kinds of play".

[66] It also took second place for Most Popular Game in the 1991 Flagship PBM Awards in Canberra, Australia (behind El Mythico).