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

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

Optimization · Pure Optimization
A recruitment RPG where building your 108-star army and optimizing rune strategies is the strategic spine.
Portal leans Optimization (Pure Optimization); Suikoden leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
Suikoden
Basic menu combat with minimal timing sensitivity
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.
Suikoden
All enemies scripted; castle battles use fixed logic
Suikoden leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Suikoden
Random encounters and some rune drop RNG add minor chaos
Portal leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
Suikoden
108 Stars recruiting order and rune attachment optimization define efficient runs
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.