head to head
Neither is simply harder - they are hard in different places. 428: Shibuya Scramble demands more variance; Portal 2 demands more execution.

Optimization · Pure Optimization
A live-action visual novel weaving five strangers' stories together across one chaotic day in Shibuya.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
428: Shibuya Scramble leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
428: Shibuya Scramble
Reading and choosing only
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.
428: Shibuya Scramble
No opponent, only branching script
Portal 2
No opponent; puzzles are static.
428: Shibuya Scramble leans clearly harder on variance.
428: Shibuya Scramble
Cross-character consequences hidden until triggered
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
428: Shibuya Scramble
Mapping timeline interactions to dodge bad endings
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.