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
Landmark scripted FPS following Gordon Freeman through the Black Mesa disaster.

Optimization · Practiced Mastery
The sequel takes Torque to Baltimore to fight slavery-themed monsters while his morality shapes the story.
Half-Life leans Execution (Practiced Mastery); The Suffering: Ties That Bind leans Optimization (Practiced Mastery).
Half-Life leans a little harder on execution, though the gap is small.
Half-Life
Combat aim and infamous platforming sections
The Suffering: Ties That Bind
Gunplay and monster-form brawling demand decent reflexes
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Half-Life
Marines flank by script, not by modelling you
The Suffering: Ties That Bind
Enemy archetypes run scripted behaviour, never adapt
The Suffering: Ties That Bind leans a little harder on variance, though the gap is small.
Half-Life
Set pieces surprise only on first run
The Suffering: Ties That Bind
Unknown encounters and branching morality first time
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Half-Life
Resource routing and encounter knowledge for speedruns
The Suffering: Ties That Bind
Combat systems and morality routes converge with knowledge
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.