You have a small starfreighter, and one way to make money is by buying goods where they're inexpensive, loading them up in your cargo hold, and flying somewhere where they're expensive to sell them.

Eventually you realize that it makes sense to pay other freighters to help you carry stuff so you can make more per trip---but since they charge a daily rate, at what point is it worth it? And does it make sense to risk it all ('cause, you know, space pirates) putting your life savings into a load of expensive opals which will make you a ton once you arrive, or should you play it safe and stick to inexpensive but barely-profitable foodstuffs? If you've got an appetite for risk, you can carry drugs or illegal biological weapons, both of which will make you a ton of money, but will cause law enforcement to attack if you're scanned.

It's a sort of mini-version of EVE this way, in that it's the only game I've made a spreadsheet for.