Most modern PC or console games take from one to three years to complete, where as a mobile game can be developed in a few months. The length of development is influenced by a number of factors, such as genre, scale, development platform and number of assets.
Some games can take much longer than the average time frame to complete. An infamous example is 3D Realms' Duke Nukem Forever, announced to be in production in April 1997 and released fourteen years later in June 2011. Planning for Maxis' game Spore began in late 1999; the game was released nine years later in September 2008. The game Prey was briefly profiled in a 1997 issue of PC Gamer, but was not released until 2006, and only then in highly altered form. Finally, Team Fortress 2 was in development from 1998 until its 2007 release, and emerged from a convoluted development process involving "probably three or four different games", according to Gabe Newell.