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 top-down co-op shooter testing aim and upgrade optimization against alien swarms.

Optimization · Practiced Mastery
An atmospheric open-zone survival shooter set in the Chernobyl exclusion zone.
From Space leans Execution (Practiced Mastery); S.T.A.L.K.E.R.: Shadow of Chernobyl leans Optimization (Practiced Mastery).
From Space leans a little harder on execution, though the gap is small.
From Space
Twin-stick aiming and dodging swarms is core
S.T.A.L.K.E.R.: Shadow of Chernobyl
Ballistic gunplay punishes sloppy aim
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
From Space
Aliens are scripted/random, not adaptive minds
S.T.A.L.K.E.R.: Shadow of Chernobyl
A-Life feels alive but doesn't model you
S.T.A.L.K.E.R.: Shadow of Chernobyl leans a little harder on variance, though the gap is small.
From Space
Random spawns and drops add chaos
S.T.A.L.K.E.R.: Shadow of Chernobyl
Anomalies, mutant spawns, and artifact RNG hide information
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
From Space
Weapon upgrades and squad coordination reward planning
S.T.A.L.K.E.R.: Shadow of Chernobyl
Artifact economy, routes, and stash knowledge converge
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.