I recently replayed both Fallout: New Vegas and Horizon: Zero Dawn, and have moved on to Fallout 4 (and the second season of the TV series) and Horizon: Forbidden West. Both franchises are open-world games—with special focus on the American southwest—set in a time long after all civilization was undone. Despite this commonality, they are on opposite ends of the cynicism/idealism spectrum.
Fallout is a pitch-black satire of American culture. Its world is fundamentally broken, and all attempts to restart civilization for a better, brighter future are doomed to inevitably fail. The world will keep breaking.
The devastation which Earth faced is actually far worse in Horizon than it was in Fallout, but there is a much more resilient hope that humanity will endure, rebuild, and eventually learn from the past.
Horizon is probably the more ‘scientifically’ plausible setting, but the general tone of Fallout might be more true to life.