head to head
Neither is simply harder - they are hard in different places. Anno 1602 demands more optimization; The Elder Scrolls V: Skyrim demands more execution.

Optimization · Pure Optimization
Island colonisation strategy about balancing population tiers against expanding supply chains.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Anno 1602 leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Anno 1602
Slow real-time pace; no dexterity test.
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Anno 1602 leans a little harder on reads, though the gap is small.
Anno 1602
AI rivals act on fixed personalities, not adaptation.
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Anno 1602 leans a little harder on variance, though the gap is small.
Anno 1602
Island fertility layouts and rival starts are hidden initially.
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Anno 1602 leans clearly harder on optimization.
Anno 1602
Population tiers and supply chains are a near-pure logistics solve.
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.