A pivotal Fallout 3 DLC moment hinged on a constantly exploding illusory mansion

The second-biggest explosion in Fallout 3 has been revealed to be a classic piece of Bethesda developer magic.

In a Twitter thread, former Bethesda artist Nate Purkeypile - who lent his talents to all of the studio's Fallout games, as well as Skyrim and Starfield - outlined the complex solution to the explosion that destroys Calvert Mansion in Fallout 3's Point Lookout DLC. 

No matter what path you take in the DLC, the mansion will blow up, but Fallout 3 didn't really feature the technology to ensure that it would stay blown up after you walked away. Purkeypile explains that "distant buildings and trees were all just one static set," meaning Bethesda ran the risk that the mansion - supposedly blown to smithereens - might "suddenly show up when you walk further away."

To help solve that issue, the team turned to the game's biggest explosion - the infamous detonation of the bomb in Megaton. That distant big bang was "the only remotely similar tech" that Bethesda had access to, showing off an explosion a long way away from the player.  But to use that tech, Purkeypile explains that the developers had to turn Calvert Mansion itself into an explosion.

As Purkeypile puts it: "the mansion is a 'distant explosion' and the house slowly shrinks over time and then spawns a new house 'explosion'. That explosion needs to keep triggering or it just goes away, because that [explosion] tech was only designed to do actual explosions." In more simple terms, Calvert Mansion was a constantly exploding illusion of a building. After the actual explosion occurred, the illusion would be turned off, revealing the real Calvert Mansion - little more than a pile of rubble.

This is far from the only example of Bethesda's development trickery. Purkeypile himself cites the famous example of the Fallout 3 train that was actually an NPC wearing a giant train hat. Recently, we've also heard about the myth of Skyrim's treasure foxes, and the way in which its iconic opening scene was almost ruined by a super-powerful bee. Purkeypile has now left Bethesda, and is now working on solo-project The Axis Unseen, a heavy metal hunting game that he's making, in part, as he travels around the US in a campervan.

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