Time Travel is one of the most complicated magicks there is, and many believe it is absurd to believe in it at all. To others its not magic at all, but could be representive of the forbidden sciences. Others, however, believe that time is much more fluid than the ordinary person may perceive. Some say that the very World of Daventry was created through time-travel during the Withdrawal from the Other World.
Unfortunately, time travel can lend itself to unforseen consequences. In the most notable example of this, the wizard Harlin the Malevolent sought to prevent his defeat at the hands of the Wanderer and so he reversed time and replaced the adventurer with a man from another time. Unfortunately for the wizard, he had accidently chosen the same individual who had defeated him, creating a paradox in which Harlin must eternally suffer defeat at the hands of the adventurer he plucked from time.
Questions concerning the identity of the gnome Rumplestiltskin and the Old Gnome encountered by Graham in the Sovereignty of Serenia center around time travel as well. If, in fact, the two gnomes are one and the same, it is suggested that Graham's final meeting with the gnome was in fact the gnome's first meeting with Graham through the means of some form of time warp or other time travel.
Choices made in the present may influence later events and create alternate dimensions (KQ) and pocket universes through paradoxes.
Real World[]
The events of Wizard and the Princess represent a classic grandfather paradox with a causal loop (predestination paradox or bootstrap paradox). The events only happened once, but on a non-linear passage through time.
In KQ lore, 'time travel' may be magical or scientific (based on physics). The exact processes of both are not clear. There are magicians, scientists, and philosophers who study it.
External Links: King's Quest Omnipedia