The stock market. I remember that I did a report on it back in grade school... and had no idea what I was talking about. I know, "buy low. Sell high" and all that, but if only there were a game to help me with it... Oh, Hey, Stockpile, as well as its expansion, Illicit Investments. There's even an Epic Edition. And it's all up on Kickstarter now.
From the campaign:
The campaign's around 5x funded with 15 days left to go before the end of trading.