head to head
Neither is simply harder - they are hard in different places. Fallout: New Vegas demands more execution; X-COM: Apocalypse demands more variance.

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

Optimization · Pure Optimization
Ambitious X-COM entry defending a single city with real-time tactical combat.
Fallout: New Vegas leans Optimization (Pure Optimization); X-COM: Apocalypse leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Fallout: New Vegas
Shooter inputs with VATS assist
X-COM: Apocalypse
Optional real-time mode adds slight dexterity.
Fallout: New Vegas leans a little harder on reads, though the gap is small.
Fallout: New Vegas
Scripted factions and enemies
X-COM: Apocalypse
Alien behavior is systematic, not adaptive.
X-COM: Apocalypse leans clearly harder on variance.
Fallout: New Vegas
Some loot and crit RNG
X-COM: Apocalypse
Hidden enemies and random raids drive uncertainty.
X-COM: Apocalypse leans a little harder on optimization, though the gap is small.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
X-COM: Apocalypse
City politics, economy and tech routing decide the war.
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.