It seems like every big iOS game these days is free-to-play--rather than charging to download the title, these games rely on in-app purchases to make money. Zynga (and other Facebook) games work the same way--play for free, but bring your credit card just in case you want to buy some coins, money, or even donuts (in the case of The Simpsons: Tapped Out) to prolong the fun. It seemed like a fad for a while, I mean, how long could people be entertained while sinking money into Farmville? The answer: long enough for a Farmville 2. The revenue brought in by the free-to-play model did not go unnoticed by big developers and publishers--in June 2011, Team Fortress 2 (TF2), VALVes extremely popular online multiplayer shooter went free-to-play, fueled by the Mann Co. Store, where players could buy hats, weapons, and other in-game, virtual items with real money. League of Legends, based off the wildly popular Warcraft 3 mod Defense of the Ancients (commonly referred to as DotA) is the free-to-play success story. Published by Riot Games, League of Legends is free to download and play and includes an in-game store similar to TF2, and was recently revealed to have twelve million daily players and over one billion play hours worldwide as of October 2012. Those numbers makes it one of the most played video games worldwide and have made Riot Games a tidy sum in the process--in 2010, Business Insider reported the company of having a revenue stream of between twenty five and fifty million dollars per year--and thats when League of Legends was only the fourth most popular game worldwide. The kicker? All of the in-game purchases available in League of Legends are purely cosmetic. None of them help players win, they just make their character look different. Lets just hope that as the industry runs wild with this trend, continues to stay away from the pay-to-win model that aided in Zyngas demise.