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

Optimization · Pure Optimization
A break-and-boost JRPG carried by job-routing and party-composition planning.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Octopath Traveler leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Octopath Traveler
Turn-based, no input demand
Portal 2
Portal placement requires some precision but timing is lenient.
Octopath Traveler leans a little harder on reads, though the gap is small.
Octopath Traveler
Scripted enemies
Portal 2
No opponent; puzzles are static.
Octopath Traveler leans clearly harder on variance.
Octopath Traveler
Hit, crit, and break rolls
Portal 2
Puzzles are deterministic with no randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Octopath Traveler
Job, break-boost, party routing deeply rewarded
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.