Previously I have talked about this idea, but here is a bit longer description.
A new SG team arrives via the stargate to a sandy planet, what their leader just calls as the "Dune" after his favorite scifi book. The newbies are excited as this is one of the first planet where their Stargate Academy training has allowed them to go offworld. The planet's name looks fitting as there are large earthworms type of predators which hunt for meat. The local stargate has got weird spike decorations on it as according to legends these animals are capable of even swallowing a stargate. The new recruits believe that whole little training was heavily focused about on emergency evacs as the team must escape back through the stargate when one of the larger earthworm will also follow them. Their SG team leader has placed a camera on the local DHD, so he follows the entrance side in real time on their base while he educates the newbies about how the wormhole works that a living person won't show up on the other side until it was not completly merged into the event horizont. They have got a few second timegap to close the Iris while the animal is still going in to the stargate, but it will never materialize on the other side. So the whole cold opening was just to establish this basic Stargate lore rule for the new viewers. The commander of the base is fuming about his education methods as he was endangering the whole base and even his team has got different opinion if this whole off-world visit was just a joke or a threat. What the bold and reckless trainer didn't know that his actions will start an even greater adventure for the Tauri.
We would learn later that the local stargate system has got a travel safety feature. So the DHD can scan the race of the dialer and it can compare the living conditions on the other side with the other DHD, so if there is any danger the light of 7th chevron will change colour or flashing or if the wormhole is already established then it will stop the wormhole before entering or copy the traveller but it will send it back to the entry site (like Anubis has done it in season 9).
So anyway what the team doesn't know that the local animals were also considered as intelligent beings so this giant wormhole was saved in the gate system's memory and it was transfered to the "collector" world. This is a new unique location within the gate system which can be reached by nine chevron. We would learn it that this collector world works like an "afterlife" where the different victims of different gate accidents are transfered. Most of these travellers are not just from the local galaxy, but rather the Milky Way and the Pegasus galaxy. Later we would discover that every time somebody "splashed" on the Iris at the SGC or Atlantis' energy shield then the gate system have transferred the travellers into this world instead of letting them die. This way we could introduce a few old enemies as imagine if the Jaffa, Genii or Wraith soldiers are still there. This high level gate function was written by the Nox, who has updated their own stargate protocoll to save them. The gate system is also enough intelligent to not post bombs or explosives there, but the dangerous animals are free to go. So we would see the insects from the episode "Bane" and obviously the above mentioned earthworm type of creature as well. We would learn it later that this world is like a dead-end within the gate systems as no survivors could dial away from there.
It would be only interesting as one of the main character's motive could be that he or she was considered dead by the SGC and he/she was left behind, but actually he/she has arrived to this unique, almost prison type of world. Or the story could be introduced as his/her partner is lost or maybe even a complete SG team was considered dead. One of the base motto of the SGC is that they don't leave people behind, but maybe it has happened in the past even if they were not aware of it.
Later our heroes would make a truce with the local troops and they promise to return everyone where they belong. They will discover that this collector world has got a unique gate position as any galaxy can be reached much easier once they have managed to break the mastercode. So even intergalactic travels could be easily maintained if the travelers are transfered through this stargate as it doesn't belong to any known gate system.
And this is how a new spinoff could start. The location could be an introduction of the "shell ship" which is an Ancient vessel which can jump from stargate to stargate as it has got a self-rebuilding stargate drive and the local DHD on board will also mimicri the gate system. Or it can have a stargate which act likes a "chameleon gate" which also copies the local stargate system and works like a member of it. That is how the team would learn how expanded is the gate systems as they have to fix the ship at first and make a deal with its last passenger etc. Then they could use this "shell ship" to find the Hub the fix the messed up stargate system in the Milky Way which need the Hub in an other galaxy and then the story goes on the SpaceGenie and his little mind games / adventures and how he has moved the whole Hub / Library from some kind of invaders who know just confused the gate system with a massive, galactic wide Attero device which prevents FTL windows in the whole Milky Way galaxy.
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The other little idea was still about the Hub / Library. If we would introduce that the Hub is capable of monitoring the physical condition of the travellers in the gate system. We could learn how this wormhole and the copies can cause some genetic degeneration and this is why the Asgard were dangered. Since they have cloned themselves the clones also had this genetic problem and basically the side-effect of the stargate travel was added in their body.
This discovery would be slightly the opposite what has happened in the first idea. So while some extra features can save travellers, it looks like the interstellar travelling can also cause some damage. If we would have a change to visit the Othala or Ida galaxy where the Lucian Alliance and/or the Vanirs will try to find some Asgard tech, then we could see how the Asgard has adapted their own gate system to the problem. The local stargates are beaming energy signals so some kind of Thor's hammer type of extra device would scan the traveller, then send the signal through the active wormhole and then the beam will transport the travellers on the other side. This is the reason they had to wear their strong exoskeletons as well if they have ever entered the wormhole. The local wormholes are extremely dangerous to unorganic life so they have tried to hold back the Replicators this way to not spread via the stargates and this was the main reason why they have decided to capture the Asgard ships. This "spinoff" would follow the situation in the used-to-be Asgard controlled galaxy as everyone wants to find an important Asgard treasure room and maybe the answer is onboard of the Odysseus. Or some wardrones would be activated by the Vanirs which would go through the stargates to conquest. There could be other VR worlds in the gate memory, there could be some locked alien races which are released now, maybe the Ragnarok was just an acting for the Ori, maybe the Asgard has been on Destiny... There are so many options here why this gate system is unique and how we can use this knowledge. The beaming through the wormhole was also established in the "Quest" so maybe even Merlin has worked together with some Asgards.