I have fond memories from childhood of endlessly playing a strategy trading game for the Apple 2 called Taipan! (I'm not shouting at you, the game name included an exclamation point.) Based on the novel by James Clavell of Shōgun fame, I'd spend hours in Taipan! sailing back and forth between ports, buying items like silk and guns and opium as cheaply as possible and then selling them at their most expensive. You can actually play Taipan! in your browser if you want to check it out yourself.
Strategy...