In the year 2999, Earth is under siege by aliens from the planet Drakkon. Using time travel technology, they have sent armies to four periods in human history, with the intention of altering history to make humankind easier to conquer in the present. The player assumes control of the "Time Lord", who has until January 1, 3000 AD to vanquish the enemy in the past, or else he will self-destruct along with the time machine.