"Mario's Time Machine" is set in the year 1993. Bowser, who has built a time machine called the "Timulator", travels back in time and steals essential artifacts from various points in human history to place on display in a museum inside his castle. Because these actions will eventually change history permanently, the player character Mario takes control of the Timulator to return the artifacts to their proper areas in time. In the NES version, Bowser also kidnaps Yoshi, who is freed upon completing the game. The gameplay focuses on teaching the player the historical significance of each artifact (and of the associated historical person); to progress through the game, the player must correctly answer questions relating to the learned information.