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.

Execution · Twitch Chaos
A kart racer where controlled chaos from random items tempers otherwise precise driving skill.

Variance · Twitch Chaos
A brutal survival platformer where you are prey in a living, indifferent ecosystem.
Mario Kart 8 leans Execution (Twitch Chaos); Rain World leans Variance (Twitch Chaos).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Mario Kart 8
precise drifting and item timing matter
Rain World
Momentum-based movement and spear throws are slippery and demanding
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mario Kart 8
minimal, mostly reacting not predicting
Rain World
Predator AI is dynamic simulation, not modeling of you
Rain World leans a little harder on variance, though the gap is small.
Mario Kart 8
item boxes are heavily randomized
Rain World
Creature placement and behavior shift unpredictably each cycle
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mario Kart 8
track lines and item strategy solvable
Rain World
Route knowledge and ecosystem mastery slowly tame the chaos
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.