Indiana Jones and the Great Circle is "closest to" Raiders of the Lost Ark and The Last Crusade.
That's according to game director Jerk Gustafsson, speaking to Xbox Wire recently following the new trailer for Indiana Jones and the Great Circle as part of the Xbox Games Showcase. "We spent countless hours just re-watching the films – especially the two movies that are closest to the game, which are Raiders of the Lost Ark and the Last Crusade," Gustafsson said.
