head to head
Neither is simply harder - they are hard in different places. Fallout: New Vegas demands more execution; The Case of the Golden Idol demands more optimization.

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

Optimization · Pure Optimization
A forensic deduction game where each frozen crime scene must be fully solved through logical elimination.
Fallout: New Vegas leans Optimization (Pure Optimization); The Case of the Golden Idol leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Fallout: New Vegas
Shooter inputs with VATS assist
The Case of the Golden Idol
Drag-and-drop word selection demands no motor skill
Fallout: New Vegas leans a little harder on reads, though the gap is small.
Fallout: New Vegas
Scripted factions and enemies
The Case of the Golden Idol
Historical tableau puzzles have one correct solution each
The Case of the Golden Idol leans a little harder on variance, though the gap is small.
Fallout: New Vegas
Some loot and crit RNG
The Case of the Golden Idol
Hidden names and roles are concealed information to uncover
The Case of the Golden Idol leans clearly harder on optimization.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
The Case of the Golden Idol
Each scene is a closed logic puzzle with exactly one valid solution
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.