The Tardis (a.k.a Time And relivant Dimension In Space) is a machine that can travel through time and space. In this mod, the Tardis does the same as its TV counterpart. You can travel through different eras of Minecraft (i.e. Cave Game, Minecraft Beta, Minecraft InDev) and travel to and fro on the Overworld and some new planets such as Mars, the Omicron Persei 8, and Gallifrey (the Doctor's home world). The Tardis can only be unlocked with a Tardis Key.