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

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

Optimization · Pure Optimization
Side-on turn-based tactics where you manually aim ricocheting bullets for a steambot pirate crew.
Castlevania: Symphony of the Night leans Optimization (Pure Optimization); SteamWorld Heist 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
SteamWorld Heist
Manual aim and ricochet shots reward steady hands
Castlevania: Symphony of the Night leans a little harder on reads, though the gap is small.
Castlevania: Symphony of the Night
Scripted bosses
SteamWorld Heist
Enemy bots follow fixed behaviors
SteamWorld Heist leans a little harder on variance, though the gap is small.
Castlevania: Symphony of the Night
Item drops and rare gear
SteamWorld Heist
Procedural ship layouts and loot drops
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
SteamWorld Heist
Crew builds, weapon picks, and turn routing carry runs
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.