Fallout and Elder Scrolls series writer Emil Pagliarulo reckons Fallout 4 is the most replayable game in the series due to factions interweaving with each other.
Speaking to GamesRadar+, Pagliarulo explains, "The interesting thing about Fallout 3 is there are no faction quests," while making note of Oblivion and Skyrim's questlines like the Thieves Guild, Fighters Guild, and Dark Brotherhood. He continues, "For Fallout 4, it was the first time we said, 'You play Skyrim, and you play these factions, but they're disconnected from the main quest. They're really self-contained. In Fallout 4, let's weave everything together'. And it was the first time we did that."
