head to head
Neither is simply harder - they are hard in different places. Age of History III demands more reads; Portal 2 demands more execution.

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

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Age of History III leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Age of History III
Map clicks need no timing or twitch
Portal 2
Portal placement requires some precision but timing is lenient.
Age of History III leans clearly harder on reads.
Age of History III
AI nations follow doctrine; humans can adapt
Portal 2
No opponent; puzzles are static.
Age of History III leans clearly harder on variance.
Age of History III
Battle outcomes and events add some chance
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans a little harder on optimization, though the gap is small.
Age of History III
Economy, diplomacy and conquest planning are the whole game
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.