head to head
Neither is simply harder - they are hard in different places. Kathy Rain demands more variance; Portal 2 demands more execution.

Optimization · Pure Optimization
A 90s-set mystery adventure following a motorcycle-riding journalist into her hometown's secrets.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Kathy Rain leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Kathy Rain
No physical demands
Portal 2
Portal placement requires some precision but timing is lenient.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Kathy Rain
No adaptive opponent
Portal 2
No opponent; puzzles are static.
Kathy Rain leans clearly harder on variance.
Kathy Rain
Mystery beats are hidden only until discovered
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
Kathy Rain
Fixed puzzle and dialogue chain; one solution path
Portal 2
Solving the puzzle's logic IS the entire game.
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.