Yankee Trader, by Alan Davenport, is a "door" text-based game released in 1990 from the BBS era, which ran on MS-DOS BBSes. It is similar to TradeWars 2002 and was originally released in 1987 as Trade Wars 1000. One year later, Trade Wars 2002 adopted most, but not all of Yankee Trader's innovations. Each user is the commander of a starship. You travel about the galaxy using modified MUD commands (instead of moving N,S,E,W, you move to an adjacent "sector" number). The sectors were linked more or less randomly, with a combination of two-way links and one-way links. The object of the game is to dominate the galaxy. This was accomplished by finding ports in sectors, buying commodities (ore, organics, or equipment), and transporting them to other sectors' ports and sell them (hopefully at a hefty profit—each sector's port bought or sold each commodity for a different price, as their balance of commodities changed with trade. If "Port 1" had excess of "ore" (low price), but no "equipment" (high price), one could stock up on ore, take it to "Port 2" that lacks ore, but has equipment. By selling the ore, buying the equipment, and returning to "Port 1" and repeating, profit could be made. Players could create home bases as well in the form of planets, for stockpiling commodities, money, or weapons.
This tedium was made easier with macros which could be programmed in the game itself, where you could watch many such trips scroll by with each keyboard entry. The size of the galaxy was configurable by the BBS system operator, defaulting to 3000 sectors. A larger galaxy size allowed more players to effectively hide when they logged off for the day. As this was a one-player-at-a-time game, each player was limited to a certain number of "moves" per day, which could be around one hundred or in the thousands, depending on how the BBS system operator configured the game. After you were done with your "moves", you would be left sitting wherever you were—various defenses could be set up just in case you were "found" by another player before the next day. Colonizing planets, protecting them by building massive fleets, battling with other users' planets and trade routes were also a major part of the game.
Two types of computer controlled characters, the Xannor and mercenaries, also made moves during a nightly maintenance event. In various ways these computer controlled characters add additional threats to stationary defenses and planets (stealing resources from or directly attacking them), and benefits to active players. Players who locate mercenaries can bribe them to join and players who kill Xannor receive additional charge per day and also generate sales at Earth.
Alan Davenport has relayed that as of 2004, he no longer has the source code for Yankee Trader.
One major unresolved exploit exists in the gameplay. Ownership of "Earth" allows a player to recover 100% of all money spent at Earth. This effectively allows multiple players or a single player with multiple accounts to purchase an unlimited number of fighters, ground forces, and shield batteries because the money is never used up, only transferred back and forth between two accounts without loss. A patched version of the game exists that prevents this exploit.