head to head
Neither is simply harder - they are hard in different places. Portal demands more execution; The Legend of Heroes: Trails in the Sky demands more variance.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.

Optimization · Pure Optimization
Character-driven turn-based JRPG with a deeply customizable orbment magic system.
Portal leans Optimization (Pure Optimization); The Legend of Heroes: Trails in the Sky leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
The Legend of Heroes: Trails in the Sky
Turn-based menus only
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
No adversary modeling player.
The Legend of Heroes: Trails in the Sky
Scripted encounters, no adaptation
The Legend of Heroes: Trails in the Sky leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
The Legend of Heroes: Trails in the Sky
Minor turn-order and drop randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
Pure puzzle-solving optimization.
The Legend of Heroes: Trails in the Sky
Orbment quartz setups and turn-bonus manipulation
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.