I really liked the concept! The B.N.T.G. was well used, and while at first I was scared the twist would be the overused "the level is actually dangerous :(", I was happy to see it was not the case. The dynamic between the groups was very interesting.
However, the twist was unfortunately underdevelopped. The catch happened almost immediately. It would have been more interesting to see BR's influence there growing with time, with both BNTG and BBAR (a group you mentionned was working with BNTG but didn't use afterward), where they would see the level being more and more anomalous, with cristals disappearing, unknown sounds of constructions, unconfirmed sight of robotic beings (just random ideas ofc)… making them doubt, first wondering if it is due to the very level, but finally, with your BR building mention, concluding with the climax of the mystery. It would have allowed for a more thrilling read, while showcasing the interactions between the mentionned groups more.
With a more developped twist, I would definitely upvote this page, but as is, it will remain a novote, but it's closed to an upvote! The concept is here, the execution simply needs more devlopment towads the end.