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

Optimization · Pure Optimization
The definitive Johto adventure, adding animated sprites and the Suicune storyline across two regions.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Pokemon Crystal Version leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Pokemon Crystal Version
Menu-driven battles; zero hands requirement
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Pokemon Crystal Version leans clearly harder on reads.
Pokemon Crystal Version
Scripted trainers; human link battles are optional
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Pokemon Crystal Version leans a little harder on variance, though the gap is small.
Pokemon Crystal Version
Encounter and catch RNG, shiny odds, crit rolls
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Pokemon Crystal Version leans a little harder on optimization, though the gap is small.
Pokemon Crystal Version
Type charts, movesets, and two-region routing 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.