Merchant Colony is a trading strategy/simulation game during the colonial age (18th century) designed by David Lester. It was published by Impressions in 1991 for DOS, Amiga, and Atari ST.
The year is 1700, and you are a merchant prince who wants to build up his trading company. You can explore the world and build new colonies you must manage and defend with your soldiers. When they can sustain themselves, they will eventually produce surplus goods you can sell. Of course, you will need ships to sell and make money traveling the world.
The game is not easy, and this is probably the reason why it didn't have a huge success, but it's a game that has definitely been underestimated.