head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is optimization, and it is a single point.

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

Optimization · Pure Optimization
A streamlined immersive sim where biomod builds and route choice outweigh combat skill.
Castlevania: Symphony of the Night leans Optimization (Pure Optimization); Deus Ex: Invisible War 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
Deus Ex: Invisible War
Forgiving FPS combat with stealth options.
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
Deus Ex: Invisible War
Enemy AI is simple and scripted.
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
Deus Ex: Invisible War
Level secrets are unknown only on first pass.
Deus Ex: Invisible War leans a little harder on optimization, though the gap is small.
Castlevania: Symphony of the Night
Build crafting and sequence breaks
Deus Ex: Invisible War
Biomod choices and route selection are the deciding layer.
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.