BBS door games are computer games played on bulletin board systems.  These games were often called "doors," "chains," or "externals" because they were external applications that ran outside of the main BBS program.
There were many genres of door games. Some of the most popular included:
- Strategy games such as TradeWars 2002, Solar Realms Elite, Space Dynasty, and Barren Realms Elite
- Role playing games such as Legend of the Red Dragon, Arrowbridge and Assassin
- Board- and card-style games such as Global War and Global Backgammon
The reliance on telephone technology resulted in some characteristics of door games:
- Because most BBSes had only one phone line, door games tended to be asynchronous: multiple players could not play a game together in real time. Most door games took a turn-based approach, where multiple players each had a set number of turns available each day. 
- Door games were usually local and highly social. Because users accessed a BBS by phone, they tended to call BBSes within their own area code in order to avoid long-distance charges. 
- Because of low bandwidth, most door games could offer only simple text graphics, and instead emphasized gameplay and social interaction. In this way, BBS door games were similar to interactive fiction of the 1980s or "social games" popular today on platforms like Facebook and iOS. Andrew Chen has said: "The primary advantages of a persistent, continually updated world with social gameplay far outweighed the fact that downloadable single player games had much better graphics." Some authors tried to side-step the graphical limitations of BBS technology by writing stand-alone graphical front-end clients. 
The multiplayer nature of many BBS door games led to a highly social experience. Games such as Global War or Solar Realms Elite facilitated this by offering messaging systems players could use to communicate within the game. Treaty offers, gossip, and demands were common. 
Door games on this wiki
- Alpha Colony VI
- Planetary Conquest
- The Clans
- Food Fight
- Final Frontier
- Esterian Conquest
- Shadow Board
- Board Master
- BBS Simulator
- Swords of Chaos
- BBS door game
- The Pit
- Murder Motel (PC)
- Land of Devastation
- Operation Overkill II
- Ultimate Universe
- The Arcadian Legends
- Dungeon Master
- Global War
- BBS door
- Falcon's Eye
- VGA Planets
- TradeWars 2002
- Legend of the Red Dragon
- Phantasia (video game)
- Pyroto Mountain
- Category:Major BBS games
- Trade Wars
- STellar Chaos
- Kannons and Katapults
- Space Empire Elite
- Space Dynasty
- Solar Realms Elite
- Planets: The Exploration of Space
- Yankee Trader
- Barren Realms Elite
- Cripple Smash
- BBS Archives - Collection of BBS doors and related files
- BBSFiles.com - door games, utilities, and forums
- BBS doors at the Open Directory Project
- "BBS Door games". Moby Games. Retrieved 18 October 2012.
- Andrew Chen (26 Aug 2009). "BBS Door Games: Social Gaming Innovation from the 1980s". Inside Social Games. Retrieved 1 Feb 2013.
- Wolf, Mark J P (2008). The Video Game Explosion: A History from PONG to PlayStation and Beyond. ABC-CLIO. p. 155.
- Edwards, Benj. "The Internet's Forgotten Games". PC Magazine. Retrieved 18 October 2012.
- Wolf, Mark J P (2012). Encyclopedia of Video Games: The Culture, Technology, and Art of Gaming. ABC-CLIO. p. 568.
- Morrow, Blaine Victor (1996). Dial Up!: Gale's Bulletin Board Locator. Gale.
- Tresca, Michael J (2010). The Evolution of Fantasy Role-Playing Games. McFarland. p. 93-94.
- Jon Radoff (24 May 2010). "History of Social Games". Retrieved 9 Jan 2013.
Bobby Blackwolf (6 July 2008). "PS3 2.40 Firmware, Ticket To Ride, Mega Man 9". The Bobby Blackwolf Show (Podcast). Guest: Rob Roberts. Retrieved 22 April 2013.
A lot of the BBS door games they were designed so only one person would be playing it at a time because a lot of the BBSes maybe only had one or two nodes.
- Tom, Knapp (3 Mar 1995). "Games? Did you say computer games?". Intelligencer Journal. LNP Media Group Inc. ISSN 0889-4140.
Sure, they can be graphic-lite, but they're competition-heavy. These aren't human-vs.-computer affairs - I'm talkin' interactive combat with one, several or dozens of other users. Some boards are linked to other BBSes, expanding the playing field to hundreds.
- Baker, Derek; Wice, Nathaniel, eds. (1994). netgames. Michael Wolff & Company. p. 11-12. ISBN 0-679-75592-6.
On the commercial services and BBSs some games come with fancy graphical 'frontends' that you run on your computer. ... Frontend programs replace typed commands and word descriptions with colorful pictures and point-and-click options.
- Josh Renaud (13 Feb 2013). "Solar Realms Elite memories". Break Into Chat. Retrieved 9 Sep 2013.
- Joe, DeRouen (May 1996). ""Online BBS Gaming: Still alive and kicking"". Computer Currents. Computer Currents Publishing Corp. ISSN 1090-7572. Archived from the original on 1996-05-17. Retrieved 2013-08-27.
Players in LORD can do a lot more than just fight; they can flirt with non-player characters and other players alike (and even get married!) ...
- Lasay, Fátima (2004). "No Carrier and Other Stories from Philippine BBS Culture" (PDF). Read_Me: Software Art & Cultures: 49. ISBN 8798844040.
However, what made 'Digiteer' quite popular was the door game. ... We also made images and absurd stories based on the door game 'Legend of the Red Dragon' ... A few people also began developing their own door games.
Amit Patel. "Amit Patels' home page". Retrieved 19 October 2012.
Believe it or not, someone has written a strange sci-fi story that mentions the characters waiting for their SRE turns! And there are other stories about SRE too.