head to head
Grim Dawn asks more than Portal, and the gap is variance.

Optimization · Pure Optimization
A deep dual-class build system where optimising passive constellations and resist thresholds is the core challenge.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Grim Dawn leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Grim Dawn
Boss fights and Crucible have limited twitch demand
Portal
Portal placement timing modest.
Grim Dawn leans a little harder on reads, though the gap is small.
Grim Dawn
Solo and co-op PvE throughout; no adaptive opponent
Portal
No adversary modeling player.
Grim Dawn leans clearly harder on variance.
Grim Dawn
Drop RNG and component rolls add moderate hidden information
Portal
Deterministic chambers; no randomness.
Grim Dawn leans a little harder on optimization, though the gap is small.
Grim Dawn
Dual-class mastery system and devotion tree are extensively solvable
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.