Fallout: New Vegas

Obsidian's 2010 entry was built in eighteen months on Fallout 3's engine by a team including original Fallout developers, and it is the one the series' fans point to. You are a courier shot in the head over a package, and the Mojave you wake into is a genuine political situation rather than a wasteland: the New California Republic, Caesar's Legion, Mr House in his tower and the option to take Vegas yourself. All four are viable endings with faction reputation tracked independently, so the game accommodates being a hero to one side and a war criminal to the other. The writing is denser and more adult than Bethesda's, quests routinely have four or five resolutions, and skill checks unlock dialogue rather than just doors. It shipped badly bugged and its Metacritic score cost Obsidian a bonus, which became one of the more notorious stories of the era. Hardcore mode adds food, water and sleep. Old World Blues and Lonesome Road are essential. The community has patched it for fifteen years.