head to head
Neither is simply harder - they are hard in different places. Surviving the Aftermath demands more variance; The Elder Scrolls V: Skyrim demands more execution.

Optimization · Pure Optimization
Post-apocalyptic colony management with world-map expeditions.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Surviving the Aftermath leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Surviving the Aftermath
no reflex
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Surviving the Aftermath
no adversary
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Surviving the Aftermath leans clearly harder on variance.
Surviving the Aftermath
weather, raids, world events
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Surviving the Aftermath leans a little harder on optimization, though the gap is small.
Surviving the Aftermath
colony layout and specialists
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.