head to head
Neither is simply harder - they are hard in different places. Heroes of Might and Magic III demands more reads; The Elder Scrolls V: Skyrim demands more execution.

Optimization · Pure Optimization
Legendary turn-based strategy of castle economies, hero armies, and tile-perfect logistics.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Heroes of Might and Magic III leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Heroes of Might and Magic III
Turn-based; zero dexterity
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Heroes of Might and Magic III leans clearly harder on reads.
Heroes of Might and Magic III
Human multiplayer adds bluffing; AI is mappable
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Heroes of Might and Magic III leans clearly harder on variance.
Heroes of Might and Magic III
Map fog, creature banks, and morale rolls
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Heroes of Might and Magic III leans clearly harder on optimization.
Heroes of Might and Magic III
Hero chains, build orders, and combat math are deeply solvable
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.