head to head
Neither is simply harder - they are hard in different places. Sid Meier's Civilization IV demands more reads; The Elder Scrolls V: Skyrim demands more execution.

Optimization · Pure Optimization
Deep empire optimisation over a hidden map against mappable AI.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Sid Meier's Civilization IV leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Sid Meier's Civilization IV
Turn-based clicks have no physical ceiling
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Sid Meier's Civilization IV leans clearly harder on reads.
Sid Meier's Civilization IV
Human multiplayer adds diplomacy reads; AI is mappable
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Sid Meier's Civilization IV leans clearly harder on variance.
Sid Meier's Civilization IV
Map generation and unrevealed terrain drive early decisions
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Sid Meier's Civilization IV leans clearly harder on optimization.
Sid Meier's Civilization IV
Tech paths, tile yields and expansion math dominate outcomes
The Elder Scrolls V: Skyrim
Skill stacking, enchant loops, and exploits are deeply solvable.
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.