Sorry, should of cleared that out too, I didn't mean that the player would have to spend 2 hours, it would just stick around for 2 hours like the Iron Banner does, they would only be at the event however long it takes.

Okay but would it still stop them from doing anything else?

No, not at all, it would be just like the traditional public event like the ones in Old Russia, like defending the WARSAT, etc. It would just be at a larger scale by collecting all of the kills and points the community picks up. As the community succeeds and fails, the game could maybe process which of the outcomes was more dominant. If the percentage of success is more, they pass. If the percentage of failure is higher, the aliens take over making the area far more dangerous than it was in its original state for about a week/month or whatever. :)

That makes sense but they would have to be careful with the levelling of enemies as there would be risks of people being unable to make an impact or finding it too easy

They could maybe set the enemy levels to scale depending on the player levels?