Stargate SG-21 is a game based in the Stargate universe and SG-21 is run out of Stargate Command (SGC) led by Brigadier General O'Neill.  This game will be run in parallel to the TV show starting at th 8th season.  Here are events that are fact for in game knowledge:

Mike H. is the GM of Stargate SG-21 and GM information can be found here.

Home World Security run by General Hammond has setup a new branch of the division. That branch is related to Off-world intelligence gathering. You proud personnel are a part of the intelligence division. SG21 (you) is the flagship team for that division. SG22 - SG30 are your backup. They, as you, are devoted to intelligence gathering and reporting up through O'Neill to Hammond. You will obviously have more responsibilites than intelligence gathering, but that is your primary.

Nearly everyone in the SGC knows when and where the Stargate was discovered. A few even know who found it. But what happened to the Stargate after the discovery in 1928? Most believe it fell into the hands of the U.S. government, and indeed by 1945. The Americans were conducting secret tests on the device. But its route from Giza to Washington was more circuitous than most could imagine, and passed through a very dark and terrible place in the process.

The Stargate and all the artifacts found in the area were originally taken to the Egyptian Museum in Berlin. Prof. Paul Langford, who was in charge of the expedition, received permission to begin tests on the Stargate to discover its purpose. The research came to naught, though it had more to do with lack of funding (Germany was in precarious financial straits at the time) than any fault of Dr. Langford's.

This all changed once Adolf Hitler became Chancellor of Germany. Intrigued by the Stargate's occult possibilities, Hitler considered the device one of his "prized possessions" and authorized generous funding into its research. Langford had fled Germany with his daughter to the United States when the Nazis took power, so the Fuhrer assigned a military general as a replacement. Under his eye the Nazis soon uncovered a second device - the DHD - which made their work considerably easier.

In 1939, just after the beginning of the war, a breakthrough took place: the Stargate opened. The address dialed was found by piecing together some of the stone fragments found at the dig site. Several explorers were sent through to investigate. Only one returned, with tales of a wondrous paradise ... which was occupied by terrible "demons." According to his descriptions, the "Heaven" he discovered had apparently been overrun by Hell and was now populated by near-human looking beings, with horrendous powers of destruction. Not wanting to let the possibility of literally conquering Heaven slip through his fingers, Hitler ordered thousands of troops and tons of equipment to be sent through the Stargate. The battle was long and difficult, but in the end, the Germans prevailed. Approximately one year after the gate opened, Heaven was in the hands of the Nazis.

By this time, some of the senior members of the German high command were beginning to chafe under Hitler's heavy handedness and emotional instability. One of most senior, Field Marshall Erwin Rommel, was terrified of the Stargate's possibilities and unwilling to leave it in the Fuhrer's hands. Heaven was rapidly becoming a thriving German colony, with thousands of "perfect" Aryan men and women passing through the Stargate to build a National Socialist Paradise. Rommel, however, had no intention of letting the colony give new resources to Hitler's cause ... or of letting the Nazi leadership use the Stargate to escape should the Allies prevail. After allowing Heaven to develop to the point of self-sufficiency, he forged a set of requisitions ordering the Stargate to be transported to the town of Rostock (along with the coverstones that held it and other attendant artifacts).

There, he would arrange for it to "disappear." never to be seen again. He deliberately left the DHD behind, so as to make operation of the Stargate impossible.

Meanwhile, the U.S. government had not lain silent. When they entered the war against Germany, Prof. Langford contacted the Roosevelt administration and shared what he knew about the Stargate. Discovering the location of the device became a top intelligence priority, and the OSS expended numerous resources in an effort to learn its location. Their big break came when Rommel's forged documents passed across the desk of an American mole at precisely the right time. The trucks never arrived in Rostock - they were seized by an elite commando unit on the shore of the Baltic Sea. The Stargate was hidden aboard a fishing vessel flying Swedish colors and surreptitiously transported to England, where it was flown by plane to the United States in early 1944.

President Roosevelt promptly ordered the gate to be researched as a possible weapon, and asked Prof. Langford to head the project. Though he disapproved of using the Stargate as a weapon, he reluctantly agreed to head up the project. Progress was slow without the DHD, but Langford and his team was very persistent. In January of 1945, as the war was winding down, they stumbled upon a second address.

Prof. Langford’s assistant Dr. Earnest Littlefield was chosen to be the first through the Stargate. Not sure what was on the other side, the professor took every precaution. He allowed the explorer wear an underwater dive suit with an oxygen hose in case the planet on the other side proved inhospitable. Immediately after Ernest stepped through, the gate shut off severing the hose. When Ernest did not return, Prof. Langford feared the worst. All further attempts to use the Stargate were shut down and the project was mothballed. With the end of the war imminent, its use as a military weapon was no longer perceived as necessary. The Stargate was taken to a government warehouse, where it remained for several decades. Prof. Langford never mentioned what happened to Littlefield and discouraged his daughter Catherine from having anything to do with the artifacts. He was largely successful, until some unknown cause renewed her interest in the Stargate sometime around 1970. Her efforts since then led to the renewal of the Stargate program, which eventually resulted in the creation of the SGC.