head to head
Neither is simply harder - they are hard in different places. Fallout: New Vegas demands more execution; Sid Meier's Civilization demands more variance.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.

Optimization · Pure Optimization
Long-horizon empire optimization over a randomly dealt but mappable map.
Fallout: New Vegas leans Optimization (Pure Optimization); Sid Meier's Civilization leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Fallout: New Vegas
Shooter inputs with VATS assist
Sid Meier's Civilization
Turn-based clicking, zero physical demand
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Scripted factions and enemies
Sid Meier's Civilization
AI leaders follow mappable personalities, not adaptive minds
Sid Meier's Civilization leans clearly harder on variance.
Fallout: New Vegas
Some loot and crit RNG
Sid Meier's Civilization
Map generation and combat rolls hide early information
Sid Meier's Civilization leans a little harder on optimization, though the gap is small.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Sid Meier's Civilization
Tech routing, expansion and economy are deeply solvable
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.