“Beware of Past Realities,” The Professor said. “A Past Reality is a Reality you used to MeToo but haven’t Traveled to in a while. When Traveling to a Past Reality you will feel an overwhelming urge to MeToo in the exact same way you used to. This is known as a TimeWarp, and it will affect you no matter how long or far you’ve been away.
Meanwhile, Time changes all Realities, and you or the Past Reality may be very different now and not be able to MeToo about the same things. These changes are known as TimeFucks, and if bad enough, they can give you Travler Vertigo, a condition of disorientation and sickness which may render you bedridden and MeToo disabled. The Vertigo is difficult to overcome without the assistance of another Traveler or The Gods and must be avoided at all costs.
To prevent the TimeWarp/TimeFuck from kicking your ass, you must have on you at all times a Grounding Device, which keeps you connected to your present Reality and allows you to find new MeToos with the Past Reality.