head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Pure Optimization
The genre-defining metroidvania with deep RPG systems.

Optimization · Pure Optimization
An open-world shooter-RPG won by perk routing and weapon mod optimization.
Castlevania: Symphony of the Night leans Optimization (Pure Optimization); Fallout 4 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.
Castlevania: Symphony of the Night
Forgiving action combat
Fallout 4
FPS aiming, VATS softens demand
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Castlevania: Symphony of the Night
Scripted bosses
Fallout 4
Scripted enemy AI
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Castlevania: Symphony of the Night
Item drops and rare gear
Fallout 4
Loot and legendary rolls
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Castlevania: Symphony of the Night
Build crafting and sequence breaks
Fallout 4
Perks, settlement, weapon mod planning
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.