head to head
Neither is simply harder - they are hard in different places. Graveyard Keeper demands more variance; Portal demands more execution.

Optimization · Pure Optimization
Macabre management sim about running a medieval cemetery as a business.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Graveyard Keeper leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Graveyard Keeper
Light action farming inputs
Portal
Portal placement timing modest.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Graveyard Keeper
Villagers run on fixed schedules
Portal
No adversary modeling player.
Graveyard Keeper leans clearly harder on variance.
Graveyard Keeper
Minor drop randomness
Portal
Deterministic chambers; no randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Graveyard Keeper
Sprawling tech trees and grind-route efficiency
Portal
Pure puzzle-solving optimization.
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.