Team Fortress is a team-based online multiplayer first-person shooter video game developed and released by Valve in 1999. Based on the 1996 Quake modification Team Fortress, the title was ported to Valve's GoldSrc engine as a way of promoting Half-Life's software development kit. Matches in Team Fortress Classic pit two teams against each other, with each team member having access to nine distinct classes. Competition takes place in a variety of scenarios, usually capture the flag, VIP protection, or territorial control. Since its release, the game has undergone significant upgrades to player models and game modes.