The coolest addition to the 'Fallout' series is totally unexpected

The new "Fallout" game is fantastic. And it's almost here!

You can buy it Tuesday for your Xbox One, PlayStation 4, or PC (or all three if you wanna be bananas).

But, while we still have your attention, we want to tell you about the most profound change to the "Fallout" series since going first-person: building, or re-building, rather.

Though you might not have realized it from the marketing, "Fallout 4" is primarily a game about re-building the remains of civilization in the Northeastern United States.

You'll do a ton of walking, from Concord to Lexington, from Cambridge to Boston Common. Along your journey, you'll encounter all sorts of characters.

Some of those characters are "settlers" - these are people trying to make it in the harsh reality of post-nuclear apocalypse Boston. Like this lady right here, who I found holed up in an abandoned train stop:

Settlers are looking for somewhere to live safely. And who better to provide them the location and protection they seek than you?

And thus begins the building process. Your first "settlement" isn't so much a town as it is an old gas station: trusty Red Rocket.

But soon you'll be taking over whole factories, or suburbs, or... the sky's the limit, really. The whole world of "Fallout 4" is yours for the taking, building up, and managing. It could've probably been named "Post-Nuclear Apocalypse City Manager 2015" instead of "Fallout 4."

The tone of the game - reconstruction - is set early on, when you meet the remnants of The Minutemen. They're a ragtag group of survivors being stretched thin by the world's "raiders" - people who rob and pillage in order to survive, often terrorizing settlers. They need your help (surprise!) so that they can begin the process of rebuilding their group, which will give the area some stability in the form of a militia. Security!

Their leader, Preston Garvey, asks you to help establish his new settlement:

Garvey and his requests explain the basics of building a settlement, from creating a farm to gathering resources to build furniture. And in doing so, Garvey educates you on the secret backbone to "Fallout 4": reconstruction.

What does this construction look like? A lot like what you'd expect it to look like! Here's a trading post being built:

And here's a guard tower under construction:

These settlements attract survivors - "settlers" - and ultimately help you produce even more resources.

Settlers are everywhere. They're a major part of what makes "The Commonwealth" - "Fallout 4's" name for the Boston metropolitan area, post-apocalypse - feel so alive. It's not hard to imagine a scattered human race, with pockets of survivors simply trying to continue surviving in a civilization that's fallen apart.

What you can build in place of the world that was destroyed by nuclear holocaust is even better, by some accounts. Like this amazing light display, for instance, featuring the game's signature "Vault Boy" character:

That's the world of "Fallout 4": in shambles, but full of life that's just barely scraping by. And with a hearty sense of humor, of course.

Building in "Fallout 4" is a brand new rabbithole to fall down for experienced "Fallout" players, and it's a delightful aside for all new players. If nothing else, it's a joyous reprieve from the business of exploring the post-apocalyptic wasteland.