Beyond the Stellar Empire (or BSE) is a play-by-email (PBM) game. Originally published by Adventures By Mail, BSE was an open-ended "space opera" with a single available game that began in playtesting in 1981. According to Stephen Marte, during the mid-1980s, like "Tribes of Crane and Midgard, BSE [was] the stomping ground of many of PBM's best power gamers". The game had two variants, one monitored by Game Masters who imposed artificial constraints, and another without constraints. Gameplay took place on a vast space stage where mega-corporations formed the dominant organizing framework, alongside various other groups that players could join to pursue tasks to advance, collaborate with other players, and progress to more senior positions such as space colony governors. Beyond the Stellar Empire placed #5 and #11 for Best PBM Game of the Year in 1987 and 1988, respectively, in Paper Mayhem, a magazine for play-by-mail games. In subsequent years, the game did not score well in Paper Mayhem reader ratings for playability, use, and product understanding. Beyond the Stellar Empire: The New System won the Origins Award for Best New Play-By-Mail Game of 1989.

The original game as run by Adventures by Mail in the United States was discontinued in the late 1990s. In the United Kingdom, a separate PBM game of Beyond the Stellar Empire ran until 2002 when the entire game was upgraded to a 21st-century version, Phoenix: Beyond the Stellar Empire (see KJC Games below). While still a PBM game, Phoenix enables players to input orders via web browser while receiving email turn results.

In the Spring 1985 issue of Flagship, John Muir stated that the game had been operating for three years, putting its initial publication at 1982. In the January 1983 issue of The Space Gamer, Adventures By Mail stated that they had processed more than 20,000 turns of BSE. Muir stated that, in 1985, BSE was human moderated with computer assistance. This continued to 1990.

Reviewer Stephen Marte stated in 1987 that he had contact information for 150 PBM players but speculated that as many as 450 actually played the game.

In the January/February 1990 issue of Paper Mayhem, a magazine for play-by-mail games, Mike Popolizio, Liz Leblanc, and Marti Popolizio described a redesign conducted on BSE. The overhaul included faster turnaround times for turns, additional options for diplomacy, increased ability to implement player suggestions, introduction of black-markets, and other changes.

In a 1992 issue of Paper Mayhem, Wayne Alexander identified two variants of Beyond the Stellar Empire: the Capellan Periphery and the Draconian Variant. Alexander noted that the Capellan Periphery was the initial variant and was open-ended in the sense that it had no victory conditions–players could continue to progress through work and expenditures, requesting and completing assignments, acquiring larger ships and colonies, etc. However, he lamented that the Capellan Periphery was not truly open-ended in that the Game Masters (GMs) eventually would impose an artificial constraint on play that he called "The Wall". This didn't prevent the players from having an enjoyable playing experience, but it limited "power players". In other words, according to Alexander, "The Capellan Periphery has a lot of sizzle, but the steak is just dog meat." The Draconian Variant, while nascent in 1992, and saddled with some minor gameplay challenges, put players on the "ground floor" of a truly open-ended game, causing Alexander to describe it as one "with very little sizzle at this point, but the steak is filet mignon in potential".

Diplomacy played a part in gameplay. A player in 1987 stated that he received an average of 47 letters weekly while playing.

The game took place on a vast space stage. Stephen Marte stated the following about the field of play in 1987: