head to head
Fallout: New Vegas asks more than Agatha Christie: Hercule Poirot - The London Case, and the gap is execution.

Optimization · Pure Optimization
A detective adventure about gathering clues to solve an authored murder case.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.
Agatha Christie: Hercule Poirot - The London Case leans Optimization (Pure Optimization); Fallout: New Vegas leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Agatha Christie: Hercule Poirot - The London Case
Point-and-click interaction needs no physical skill
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.
Agatha Christie: Hercule Poirot - The London Case
Suspects are scripted, not adapting to your deductions
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.
Agatha Christie: Hercule Poirot - The London Case
Clues hidden until found, but fully authored
Fallout: New Vegas
Some loot and crit RNG
Fallout: New Vegas leans clearly harder on optimization.
Agatha Christie: Hercule Poirot - The London Case
Connecting evidence to solve the fixed case is the work
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.