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

Optimization · Pure Optimization
Card-battle strategy testing deckbuilding math against draw luck.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.
Etherlords II leans Optimization (Pure Optimization); Fallout: New Vegas leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Etherlords II
Turn-based card play, no dexterity
Fallout: New Vegas
Shooter inputs with VATS assist
Etherlords II leans a little harder on reads, though the gap is small.
Etherlords II
Mostly AI duels; rare human matches add light bluffing
Fallout: New Vegas
Scripted factions and enemies
Etherlords II leans clearly harder on variance.
Etherlords II
Card draws decide what each duel offers
Fallout: New Vegas
Some loot and crit RNG
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Etherlords II
Deck construction and mana sequencing are deeply solvable
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.