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.

Variance · Twitch Chaos
A brutal survival platformer where you are prey in a living, indifferent ecosystem.

Execution · Twitch Chaos
An open-world survival shooter set in a hostile irradiated Zone full of anomalies and scarce supplies.
Rain World leans Variance (Twitch Chaos); S.T.A.L.K.E.R. 2: Heart of Chornobyl leans Execution (Twitch Chaos).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Rain World
Momentum-based movement and spear throws are slippery and demanding
S.T.A.L.K.E.R. 2: Heart of Chornobyl
Lethal gunfights with recoil, bleed, and ballistics punish sloppy aim
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Rain World
Predator AI is dynamic simulation, not modeling of you
S.T.A.L.K.E.R. 2: Heart of Chornobyl
A-Life NPCs roam but never model the player adaptively
Rain World leans a little harder on variance, though the gap is small.
Rain World
Creature placement and behavior shift unpredictably each cycle
S.T.A.L.K.E.R. 2: Heart of Chornobyl
Anomalies, emissions, stash rolls, and unknown Zone layouts hide information
S.T.A.L.K.E.R. 2: Heart of Chornobyl leans a little harder on optimization, though the gap is small.
Rain World
Route knowledge and ecosystem mastery slowly tame the chaos
S.T.A.L.K.E.R. 2: Heart of Chornobyl
Artifact hunting, gear upkeep economy, and routing through the Zone
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.