head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Optimization · Pure Optimization
A wave-defense RTS testing economic and defensive optimization against scripted hordes.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.
Diplomacy is Not an Option leans Optimization (Pure Optimization); Fallout: New Vegas leans Optimization (Pure Optimization).
Fallout: New Vegas leans a little harder on execution, though the gap is small.
Diplomacy is Not an Option
Fast unit micro helps but isn't the ceiling
Fallout: New Vegas
Shooter inputs with VATS assist
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Diplomacy is Not an Option
Enemy hordes follow scripted waves, not adapting
Fallout: New Vegas
Scripted factions and enemies
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Diplomacy is Not an Option
Some map and event variation, mostly fixed
Fallout: New Vegas
Some loot and crit RNG
Diplomacy is Not an Option leans a little harder on optimization, though the gap is small.
Diplomacy is Not an Option
Economy, defenses and army composition against scaling waves
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
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.