I picked up the portal gun last phase, it allows us to create two portals to travel from one to another, but I am asking for clarification/more details on how it exactly works.

Also, sadly, it requires a fusion cell to work... *sigh*

So the portal gun creates a portal in the room it is in, and then we have to use it in another room to create the second room, essentially, it's a fast travel between one room to another, and if we create a third portal after the second, the first one disappears but it would need a fusion cell after that, so we have that in our back pocket if we ever need to plan ahead or anything.