Many game developers keep a free-to-play version running so people can try out their game before paying the membership costs. It also helps in that the game may receive higher ratings, attracting more people to it. Other developers, for example softnyx, or Maple Story, generate revenue by selling in-game items that significantly enhance the player's in-game experience. In-game items can be purely cosmetic (vanity items), enhance the power of the player (power items), or accelerate progression time (booster items).
The term free-forever game (FF2P) is used to distinguish MMOGs that promise to never charge a monthly fee from those that are currently free-to-play but may become pay-to-play in the future. It applies only to online games because while a conventional singleplayer freeware game becomes free-forever as soon as it is downloaded to the player's hard drive, a free online game may start charging a fee and instantly transform into a pay-to-play game. Others conduct free-to-play services as for gaming to be substantially alive but charging through other means, as for in-game items and money.
There are many games specifically designed around the free-to-play model. Examples are Rohan: Blood Feud, Fiesta, Dragonica, Runescape, Kart Rider, and Maple Story. The biggest amount of monetized (revenue generating) free-to-play games are developed in Korea, where they dominate 90% of the gaming market. Companies that pioneered the Korean monetized free-to-play model are Nexon, NHN, YNK Interactive and Neowiz.