head to head
Grim Dawn asks more than Fallout: New Vegas, and the gap is variance.

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

Optimization · Pure Optimization
A deep dual-class build system where optimising passive constellations and resist thresholds is the core challenge.
Fallout: New Vegas leans Optimization (Pure Optimization); Grim Dawn leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout: New Vegas
Shooter inputs with VATS assist
Grim Dawn
Boss fights and Crucible have limited twitch demand
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
Grim Dawn
Solo and co-op PvE throughout; no adaptive opponent
Grim Dawn leans clearly harder on variance.
Fallout: New Vegas
Some loot and crit RNG
Grim Dawn
Drop RNG and component rolls add moderate hidden information
Grim Dawn leans a little harder on optimization, though the gap is small.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
Grim Dawn
Dual-class mastery system and devotion tree are extensively 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.