Riot Games, developer and publisher of the long-anticipated League of Legends RTS game for PC, has announced that the game will launch as a freemium title rather than a traditional retail title when it is released in September 2009. The game will offer players cosmetic virtual goods that can be used to customize their avatar and aspects of the game experience. The cosmetic virtual goods will be purchased with a virtual currency called Riot Points that users can purchase with real money.

League of Legends will also launch with a second currency called Influence Points that is only earned by completing matches with other players. Players will spend Influence Points on upgrades that make their avatars more powerful. Players can also earn certain amounts of Riot Points at the end of a completed match. As with many games currently opting for the freemium model that still want to cater to core gamers, Riot Games is emphasizing that players who spend a lot while playing won’t have a power advantage over players who don’t.

Although the base game with League of Legends will be freemium, Riot Games is offering a physical “Collector’s Pack” version of the game for $29.99 that ships with the sorts of bonuses players usually get with pre-orders. The bonuses include exclusive in-game virtual goods for customizing avatars, bonus Riot Points, and some Champions and Runes that otherwise would have to be unlocked. For users who pre-order the Collector’s Pack version of the game, there will also be an exclusive Champion that otherwise may not be obtained.

Much of what makes League of Legends’s publication as a freemium game surprising is its origins in the core PC gaming community. The project began as an attempt to expand a popular fan-made mod for the PC RTS title Warcraft III. The first modification of the game was called Dawn of the Ancients and lead to further modifications. Riot Games was formed with the intent to transform Dawn of the Ancients into a wholly original title called League of Legends in 2005. The company currently employs 40 people who work full-tie on development of various aspects of the game.

Warcraft III had no microtransaction or virtual goods elements to its gameplay. Dawn of the Ancients was, like most fan-created mods, distributed entirely for free. Riot Games’s decision to launch League of Legends as a freemium title is a massive departure from the game’s development roots and a sign of how influential the freemium payment model is becoming in gaming. How League of Legends performs when it launches this fall will probably say a lot about how receptive core gamers are willing to be when it comes to virtual goods and microtransactions.