head to head
Fallout: New Vegas asks more than Divinity: Original Sin II - Definitive Edition, and the gap is execution.

Optimization · Pure Optimization
Deep tactical build crafting and elemental combo solving across set-piece turn-based encounters.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.
Divinity: Original Sin II - Definitive Edition leans Optimization (Pure Optimization); Fallout: New Vegas leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Divinity: Original Sin II - Definitive Edition
Turn-based combat removes any physical 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.
Divinity: Original Sin II - Definitive Edition
Optional PvP arena aside, AI follows mappable behaviour
Fallout: New Vegas
Scripted factions and enemies
Divinity: Original Sin II - Definitive Edition leans a little harder on variance, though the gap is small.
Divinity: Original Sin II - Definitive Edition
Initiative rolls, random loot and unknown encounters add spice
Fallout: New Vegas
Some loot and crit RNG
Divinity: Original Sin II - Definitive Edition leans a little harder on optimization, though the gap is small.
Divinity: Original Sin II - Definitive Edition
Build synergies, surface combos and positioning 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.