Gameplay

There are three ways to get income (four, if you count purchasing ingame cash with real money):
 * Shipping cargo.
 * Shipping oil.
 * Invest in shares.

Shipping
The bread and butter of the game, there are a number of factors that determines the income of your ships. The base is the size of your ship, the more cargo it hauls the higher the potential. This is multiplied by your staff's (lack of) efficiency, so anything less than 100% will lower the amount shipped. Your Load Balance, which let you decide if you go for maximum cargo or fuel efficiency, is also effecting the load on the route. Finally, the Demand of the two ports on the route are added together for the final multiplier to give the actual load of the ship. The longer the route, the more you get paid for each unit of cargo.

Containers
There is said to be a small, random modifier to the load, representing different cargo in the containers. It is worth to note that the minimum payment is $45', so running small ships on short and otherwise unprofitable routes can pay off if you can stay online and keep sending them out as soon as they arrive.

Oil
Unlike TEU, there is no fixed price per ton. Instead, the price of HFO in your bunker at the time of departure is used. This means an oil-shipper should be able to refuse to leave port if the price is too low, and instead check back once per hour to see if the price is right.

Investments
Buying stock in SM isn't day-trading. When buying the shares, you pay a commission of 8% so the price has to go up least 8% just to reach break-even. Generally speaking, this means shares is too slow to compete with the profits made from shipping during the same length of time.