head to head
S.T.A.L.K.E.R.: Clear Sky asks more than Red Dead Redemption 2, and the gap is variance.

Execution · Practiced Mastery
A cinematic open-world western leaning on shooting feel and atmosphere.

Optimization · Practiced Mastery
A S.T.A.L.K.E.R. prequel adding a dynamic faction war across the Zone.
Red Dead Redemption 2 leans Execution (Practiced Mastery); S.T.A.L.K.E.R.: Clear Sky 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.
Red Dead Redemption 2
Gunplay and Dead Eye reward aim and timing.
S.T.A.L.K.E.R.: Clear Sky
Punishing gunfights and anomaly navigation
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Red Dead Redemption 2
Enemies use scripted AI patterns, not adaptation.
S.T.A.L.K.E.R.: Clear Sky
Faction-war AI is systemic, not adaptive to you
S.T.A.L.K.E.R.: Clear Sky leans clearly harder on variance.
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
S.T.A.L.K.E.R.: Clear Sky
Dynamic faction war and emission RNG hide outcomes
S.T.A.L.K.E.R.: Clear Sky leans clearly harder on optimization.
Red Dead Redemption 2
Loadouts and routes solvable but loose.
S.T.A.L.K.E.R.: Clear Sky
Upgrade economy and territory routing reward 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.