head to head
Neither is simply harder - they are hard in different places. Age of History III demands more reads; Portal demands more execution.

Optimization · Pure Optimization
A grand strategy wargame about economy, diplomacy, and conquest across history.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Age of History III leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Age of History III
Map clicks need no timing or twitch
Portal
Portal placement timing modest.
Age of History III leans clearly harder on reads.
Age of History III
AI nations follow doctrine; humans can adapt
Portal
No adversary modeling player.
Age of History III leans clearly harder on variance.
Age of History III
Battle outcomes and events add some chance
Portal
Deterministic chambers; no randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Age of History III
Economy, diplomacy and conquest planning are the whole game
Portal
Pure puzzle-solving optimization.
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.