head to head
Neither is simply harder - they are hard in different places. Rise of Kingdoms demands more reads; The Elder Scrolls V: Skyrim demands more execution.

Optimization · Pure Optimization
Long-horizon resource and commander optimization with alliance-war prediction at the top end.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Rise of Kingdoms leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Rise of Kingdoms
Tapping commands has no physical ceiling
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Rise of Kingdoms leans clearly harder on reads.
Rise of Kingdoms
Alliance wars involve outguessing rival players' timing and targets
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Rise of Kingdoms leans a little harder on variance, though the gap is small.
Rise of Kingdoms
Commander pulls and event rolls gate progression
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Rise of Kingdoms
Build queues, commander pairings and resource math dominate
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.