Jan van der Crabben. He told listeners at a GDC Europe keynote that free-to-play developers should expect to lose 70 percent of their initial registered users.
He said that player retention is the key issue facing the new business model, and despite the fact that most players leave F2P titles shortly after registering, those who stick around for a few days will usually keep playing.
Van der Crabben, who is currently designing browser-based F2P games at Travian, pointed to World of Warcraft as a model, noting its mechanical effectiveness at retaining users by presenting them with cyclical gameplay. This amounts to "kill[ing] stuff to get better to get more abilities to kill more stuff," he said.