A classic computer game, found at least on Macintoshes since the mid-80's, wherein the player—presumably The Doctor himself—moves about the screen one step at a time, with the Daleks making one step towards the player with each of their steps. The goal is to make all the Daleks walk into each other—at which point they die—which is not terribly difficult, as they walk blindly towards the player. The danger lies in getting too close to a Dalek, at which point you die. Two methods of escaping the Daleks are available: a random teleportation, which occasionally leads you to death aside a Dalek, and the Sonic Screwdriver, which can only be used once per round and kills all Daleks within a small radius about the player.