Play as Challenger, a brave archeologist whose mission is to rescue a princess who's been kidnapped by a secret evil organization. The game offers four different types of adventures in four different ways to play, starting with a runaway train battle, exploring a vast island, and facing off against a boss. Originally planned as a port of the ZX Spectrum video game Stop the Express, which was released by Sinclair Research Ltd in 1983. Stop the Express only contained the first train level, and 3 levels were added for the release of Challenger.