|Out of universe information|
The Keeper is an android (RPG: "Friends and Foes: Stargate Season Two") that designed an interactive holographic world as a means of hibernation in Virtual reality pods for the people of P7J-989. He did not release his people once the planet became habitable again, however, as he feared that they would destroy it again. He attempted to use SG-1 to provide new experiences for the people in the chairs. However, Teal'c's Jaffa physiology and Captain Samantha Carter's modified brain from her experience as Jolinar of Malkshur's host made it impossible to draw out any of their memories, so he placed Teal'c in Colonel Jack O'Neill's memory of an attempted grabbing of a Russian spy in East Germany in 1982, in which the mission failed and Carter in Dr. Daniel Jackson's memory of when his parents died.
No matter how much SG1 members tried to change those events, the events kept repeating, so they finally refused to try again (which attempt would only make them suffer the pain of loss again). The Keeper tried to implore them to explore other options but they revealed to the spectators that their planet had regenerated itself. Therefore, the Keeper tricked SG-1 into thinking that they've arrived back at Stargate Command and posed as Major General George S. Hammond to order them back into the VR chairs. However, SG-1 escaped and tried to head back through the Stargate to show the spectators their world from SG1's memories. A struggle and chase ensued and General Hammond was revealed as the Keeper. The Keeper then accidentally lead SG1 through the VR exit portal while trying to run away. The spectators were able to follow and leave stasis themselves. The Keeper remained sure that the people would ruin the planet again, since the newly freed people were picking flowers, ruining the garden. (SG1: "The Gamekeeper")