head to head
Neither is simply harder - they are hard in different places. A Total War Saga: Troy demands more reads; Portal demands more execution.

Optimization · Pure Optimization
A historical strategy game blending Bronze Age empire-building with mythic warfare.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
A Total War Saga: Troy leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
A Total War Saga: Troy
minimal direct manual skill, command-driven
Portal
Portal placement timing modest.
A Total War Saga: Troy leans clearly harder on reads.
A Total War Saga: Troy
human multiplayer opponents bluff strategies
Portal
No adversary modeling player.
A Total War Saga: Troy leans clearly harder on variance.
A Total War Saga: Troy
minor battle randomness and morale swings
Portal
Deterministic chambers; no randomness.
A Total War Saga: Troy leans a little harder on optimization, though the gap is small.
A Total War Saga: Troy
deep economy, tech, and battle-formation mastery
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.