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

Execution · Practiced Mastery
A lean souls-like carried by hardened-parry timing and shell selection.

Execution · Practiced Mastery
The notoriously demanding side-scrolling Zelda built on tight sword duels and RPG levelling.
Mortal Shell leans Execution (Practiced Mastery); Zelda II: The Adventure of Link leans Execution (Practiced Mastery).
Mortal Shell leans a little harder on execution, though the gap is small.
Mortal Shell
Hardened parry timing demands inputs
Zelda II: The Adventure of Link
Precise sword spacing, shield stabs, brutal platforming
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Shell
Scripted bosses
Zelda II: The Adventure of Link
Ironknuckles feint but follow fixed logic
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Shell
Minor item randomness
Zelda II: The Adventure of Link
Layouts fixed, little hidden randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mortal Shell
Shell choice and upgrade routing matter
Zelda II: The Adventure of Link
XP routing, spell use, palace order 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.