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

Execution · Practiced Mastery
Fan-built ground-up remake of Half-Life with a reimagined Xen.

Execution · Practiced Mastery
The 3DS remake of Metroid II built around a precisely timed melee counter.
Black Mesa leans Execution (Practiced Mastery); Metroid: Samus Returns leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Black Mesa
Classic FPS aim and platforming sequences
Metroid: Samus Returns
Melee-counter timing defines nearly every fight.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Black Mesa
Marines and aliens follow set scripts
Metroid: Samus Returns
Counters punish scripted lunges, not adaptation.
Black Mesa leans a little harder on variance, though the gap is small.
Black Mesa
Minor enemy placement surprises first run
Metroid: Samus Returns
Fixed map and encounters.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Black Mesa
Route, resource, and encounter knowledge
Metroid: Samus Returns
Aeion management and ability routing matter.
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.