It’s amazing how successful you can be by knowing what to charge for. I actually played Farmville for a week or so, way back in late ’09. Eventually, I got tired of clicking each individual square to plow and plant and harvest, and I wondered if there was “farm equipment” to simplify the process. I figured, nah, they’d make you pay real money for that kind of thing. But to my surprise, you can buy tractors and harvesters with in-game currency. It’s the FUEL for the machinery that costs actual dollars. Which is obviously much smarter, since the machines are a one-time expense, but fuel is recurring.