head to head
Neither is simply harder - they are hard in different places. Fallout: New Vegas demands more execution; Tropico 5 demands more variance.

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

Optimization · Pure Optimization
Advancing a colonial island through history while optimizing production and appeasing fixed-script factions.
Fallout: New Vegas leans Optimization (Pure Optimization); Tropico 5 leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Fallout: New Vegas
Shooter inputs with VATS assist
Tropico 5
Interface-driven play with no physical execution ceiling
Fallout: New Vegas leans a little harder on reads, though the gap is small.
Fallout: New Vegas
Scripted factions and enemies
Tropico 5
Factions and superpowers follow scripted logic
Tropico 5 leans clearly harder on variance.
Fallout: New Vegas
Some loot and crit RNG
Tropico 5
War outcomes and election swings carry hidden randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Tropico 5
Era progression and economic chains reward systematic planning
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.