This is set in the S.T.A.L.K.E.R universe if you didn't already know and its set in an AU verse since Clear Sky still exists instead of them all dying at Chernobyl some of the important characters based of the Anomaly and Gamma mods.
Anyway the power explanation, its the celestial forge but will upgrade over time. What that means is that I will limit the perks gained to a set amount of cost. So that means the mc won't get anything above 350 cost until he does something that allows him to earn higher cost perks and so on. He will be able to gain perks from doing things obviously and this isn't based on a type earning system its merit and other things like events or whatever. (An example might be him creating a new faction specific item that becomes a symbol or clear identifying factor of the faction, or doing something like creating a water purifier or upgrading the main base in a big way. On the other hand the faction claiming an important area might also give him something like the steel mill or the southern farm)
The multiverse part of this story is that I will eventually get to the Zone expanding or opening doorways or portals to other universes and having new things arrive in the zone which could be plants, animals people items etc. While also in the original universe having other non cannon things happen to make things more interesting.
(additional note these type of chapters will not be grammer checked and will usually be written like this unless I think it should be checked in case its important)