'dropfiles', small binary or text files dropped into known locations in the BBS'
A major use of doors is for door games: computer games played on the BBS.[3] These games included strategy games such as TradeWars 2002, Food Fight!, [4]Solar Realms Elite,[5]Space Dynasty, Usurper,[6] and Barren Realms Elite.[7] There were also role-playing games (RPG), often derived from earlier email-based games. One such game was Seth Robinson's Legend of the Red Dragon,[8] and another popular dystopian RPG: Operation: Overkill,[4] another was Mutants!. BBSes often published high scores, encouraging players to beat others.[9]
InterBBS leagues allowed users of different BBSes to compete against each other in the same game. A modern version of this known as BBSlink exists allowing sysops to offer door games on their BBS which are hosted on a remote server, thereby increasing the user base of the game.
Door - Interface to normal programs
https://www.mobygames.com/game-group/bbs-door-games
The Forgotten World of BBS Door Games Explore what online gaming looked like in the early 1990s, aka Bulletin Board Systems.
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