So if I could design another Fallout game… I might not design a traditional RPG at all. Instead, think of a strategy-RPG hybrid like King of Dragon Pass – set in the Fallout universe. You’re placed in the role of the tribe’s leaders, responsible for establishing a home base, keeping your people safe and fed, exploring the surrounding wasteland, and managing relations with other tribes and factions.
You’d mold the future of your tribe by plundering knowledge from Vaults and ruins and deciding whether to utilize that knowledge/technology or keep it hidden from your people. Revealing old world secrets would always have consequences, both positive (e.g., economic or military benefits) and negative (e.g., jealousy or fear from your neighbors). Unearthing stories from the old world might unlock opportunities to change the organization and personality of your tribe - think of how old-world stories opened possibilities for Caesar or the Three Families. You’d also choose how to feed and supply your people - by looting ruins, raiding other tribes, or trying to rediscover secrets of agriculture and animal husbandry from the Vaults. Ultimately, you’d have to decide how to survive in the face of external threats. Would you build a slave empire like Caesar, establish a democratic federation of tribes, or just turn to cannibalism and prey on your neighbors? It may or may not have mass market appeal… but I’d play that game.