Time Fissures are cracks generated in the universe from the time lords reaching through from the pocket universe to the actual universe. There are several known Time Fissures and while 5 are short messages, some of these fissures allow you to reset your regeneration cycle. The fissures are found at;

  1. Yuleworld, on the platform next to the TARDIS.
  2. Motel LA, in a sideroom, before the push-able bookcase.
  3. Skaro, 1st floor of the research outpost.
  4. Graystone hall, in the autons room, opposite the door.
  5. The moon base, Lunar surface, behind the control room.
  6. Ant mound, back of the barn. (Allows regen reset)
  7. Hoover dam exterior, behind intake tower 2. (Follow the road and take the 1st left) (Allows regen reset)
  8. Goodsprings, Doc Mitchell's bedroom. (Allows regen reset)