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

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

Optimization · Pure Optimization
Story-heavy deckbuilder of clashing dice and floor-by-floor library combat.
Fallout: New Vegas leans Optimization (Pure Optimization); Library of Ruina leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Fallout: New Vegas
Shooter inputs with VATS assist
Library of Ruina
Turn-based card combat, no input precision.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Scripted factions and enemies
Library of Ruina
Scripted enemy decks, no adaptive opponent.
Library of Ruina leans clearly harder on variance.
Fallout: New Vegas
Some loot and crit RNG
Library of Ruina
Dice rolls and draws swing fights moderately.
Library of Ruina leans a little harder on optimization, though the gap is small.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Library of Ruina
Deck construction and clash math is deeply solvable.
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.