There’s no denying Fallout 4 was the big mainstream moment of the series after 3 and New Vegas successfully turned the post-apocalyptic RPG series into something more in line with The Elder Scrolls. More than a decade later, its player numbers are skyrocketing again after each season of the TV show and we’re waiting for a Switch 2 port coming later this month.

Even if a fifth mainline Fallout is nowhere to be seen, the franchise is enjoying its moment in the spotlight, and Game Informer’s excellent multi-part Oral History has been exploring the past, present, and future of the game series. When talking to Bethesda Game Studios big honcho Todd Howard and other key creatives like lead designer Emil Pagliarulo, more on Fallout 4’s genesis and success was uncovered, and it appears everyone at the studio is agreeing on that entry being the franchise’s most important one.

“In 4, we swung the other way, really making the world as dense as possible, because we came up with the whole crafting system where every piece of junk you can find, you could use to build and craft things,” lead artist Istvan Pely said of the studio’s approach to Fallout 4’s overarching world design when compared to 3. Most players would tell you what defines the fourth game is the bigger focus on sandbox elements and “endless” content generation through the settlement system and building/crafting mechanics. At the same time, longtime Fallout fans maintain the series lost its way a bit when all that surpassed its RPG core.

Regardless, Fallout 4 remains the series’ biggest success to this day, with over 25m copies sold by 2020 (who knows what the official number is nowadays) and Steam data showing it’s got the biggest concurrent players, 24-hour peak, and all-time peak numbers versus the rest of the series. Even the online-only Fallout 76, which is doing mighty fine nowadays, doesn’t compare.

Pagliarulo pointed to the gap between Skyrim and Fallout 4 being a turning point for the studio, as casual “game jams” started to push the developers to try new things that often were fun enough to be kept around as part of the next game. After The Elder Scrolls V’s Hearthfire DLC, additional experimentation led to the now-iconic settlement system that allowed players to put all the once useless loot to good use. “It was a long road to get it functional, to figure out how the U.I. is going to work. We had a sort of team dedicated to that,” Pely explained.

In the age of Minecraft becoming a sensation and player expression-oriented games taking off, that entire layer of Fallout 4 added tons of replay value to an already massive RPG. “It was our first go at [player-generated content], but it was worth it, because I think we realized, like, if we can figure this out, that can become sort of a Bethesda staple,” Pely added. After Starfield’s focus on player creations of various sorts, including spaceships, it’s easy to see how important the 2015 game’s reception was for the studio, no matter what you think of it.

More than 10 years after it launched, Todd Howard also seems impressed by how well Fallout 4 has endured: “You feel incredibly fortunate. Like, we’re talking about it 10 years later. I think it’s still probably the most played Fallout game right now, and you just feel really blessed that the fans have taken to it and stuck with it.” When you combine everything these Bethesda veterans have to say with the game’s astounding financial performance over time, it’s easy to see why Fallout 4 on Switch 2 has become a priority.