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

Optimization · Pure Optimization
Base-building strategy game about optimizing upgrade economy and raid compositions.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Clash of Clans leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Clash of Clans
Troop drop placement is forgiving
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Clash of Clans leans clearly harder on reads.
Clash of Clans
Base layouts anticipate human attackers' habits
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Clash of Clans leans a little harder on variance, though the gap is small.
Clash of Clans
Matchmaking and unseen traps add uncertainty
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Clash of Clans leans a little harder on optimization, though the gap is small.
Clash of Clans
Army comps, upgrade paths, and attack routing
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.