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.

Variance · Systems & Chaos
Careful descent through procedural depths balancing survival systems against permadeath.

Optimization · Practiced Mastery
An atmospheric open-zone survival shooter set in the Chernobyl exclusion zone.
Below leans Variance (Systems & Chaos); S.T.A.L.K.E.R.: Shadow of Chernobyl leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Below
Stamina-based combat punishes sloppy dodges and swings
S.T.A.L.K.E.R.: Shadow of Chernobyl
Ballistic gunplay punishes sloppy aim
S.T.A.L.K.E.R.: Shadow of Chernobyl leans a little harder on reads, though the gap is small.
Below
Creatures and the Darkness follow rules, not minds
S.T.A.L.K.E.R.: Shadow of Chernobyl
A-Life feels alive but doesn't model you
Below leans a little harder on variance, though the gap is small.
Below
Procedural floors, traps and loot reshape every descent
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.
Below
Survival crafting and trap knowledge converge with experience
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.