The Quest was a traditional Terracon event. It sort of started as a sort of super simple FreeForm/LARP event, and evolved over the years to take on many strange forms. The traditional Quest was some sort of fantasy adventure, with players divided into teams and wandering the camp environs interacting with various NPCs to work their way through the plot. Stranger variants on the quest have included a post-modern quest, a conspiracy theory version, a Lovecraft themed one (which culminated in the summoning of Cthulhu via mass cultist dancing of the hokey-pokey), and space pirates (with space squid).
The traditional Quest appears to have largely given way to padded weapon LARP and FreeForms.