The Gift of the Gods was a Goa'uld device found by SG-1 and SG-12 on the planet P2K-797. After it was brought to Stargate Command in 1999, it created a temporary alternate reality where nothing but the SGC existed, its Stargate being connected to the one in the main SGC. When the wormhole between the Stargates in the two realities would collapse, the released energy would be enough to destroy Earth.
However, this plan failed when the alternate Daniel Jackson returned the Gift to the main universe, closing the link between the two universes and destroying the alternate SGC. He subsequently replaced his main universe counterpart, who had been killed in a Jaffa attack on the SGC. (SG1: "Gift of the Gods")