head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Optimization · Pure Optimization
WWII grand strategy: templates, production, and focus paths.

Optimization · Pure Optimization
A 4X space strategy game about building economy, tech and conquering fleets.
Hearts of Iron IV leans Optimization (Pure Optimization); Imperium Galactica II: Alliances leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Hearts of Iron IV
pausable, micromanagement-heavy
Imperium Galactica II: Alliances
Issuing orders has no twitch requirement
Hearts of Iron IV leans a little harder on reads, though the gap is small.
Hearts of Iron IV
PvP partly, mostly scripted AI
Imperium Galactica II: Alliances
AI empires follow scripted strategies, not adaptive modelling
Hearts of Iron IV leans a little harder on variance, though the gap is small.
Hearts of Iron IV
focus tree branches, events
Imperium Galactica II: Alliances
Some randomness in combat and tech but bounded
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Hearts of Iron IV
division templates and production solved
Imperium Galactica II: Alliances
Empire economy, tech and fleet building is the whole 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.