At Gamasutra, app developer Ramin Shokrizade outlines some of the ways free-to-play game developers persuade, coerce, and trick users out of their money. There is a reason why 9 of the 10 top-grossing apps are “free” to download and play, after all.
The same goes for Facebook, where nearly all games are free-to-play.
According to Shokrizade, people aren’t paying more for these games because they are amazing; the game-makers are using some devious tricks to trick them out of their cash. Especially those who are biologically more vulnerable to their tricks, as it turns out. Children, in other words, and young adults whose ability to make smart financial decisions remains undeveloped.
Note that while monetizing those under 18 runs the risk of charge backs, those between the age of 18 and 25 are still in the process of brain development and are considered legal adults. It seems unlikely that anyone in this age range, having been anointed with adulthood, is going to appeal to a credit card company for relief by saying they are still developmentally immature. Thus this group is a vulnerable population with no legal protection, making them the ideal target audience for these methods. Not coincidentally, this age range of consumer is also highly desired by credit card companies.
The tricks aren’t illegal, just … tricky. They all use a “premium currency” instead of dollars and cents, so you don’t realize how much money you are spending. They extort you by giving you powerful items, then threatening to take them away if you don’t pay up. They start out as skill games, then convert to money games, where your ability to advance is primarily determined by your willingness to spend money:
King.com’s Candy Crush Saga is designed masterfully in this regard. Early game play maps can be completed by almost anyone without spending money, and they slowly increase in difficulty. This presents a challenge to the skills of the player, making them feel good when they advance due to their abilities. Once the consumer has been marked as a spender (more on this later) the game difficulty ramps up massively, shifting the game from a skill game to a money game as progression becomes more dependent on the use of premium boosts than on player skills.
If the shift from skill game to money game is done in a subtle enough manner, the brain of the consumer has a hard time realizing that the rules of the game have changed. If done artfully, the consumer will increasingly spend under the assumption that they are still playing a skill game and “just need a bit of help”. This ends up also being a form of discriminatory pricing as the costs just keep going up until the consumer realizes they are playing a money game.
There is a lot more in the article, which you should definitely read so you know what to look out for.