head to head
Neither is simply harder - they are hard in different places. Blackguards 2 demands more variance; Portal demands more execution.

Optimization · Pure Optimization
Deep hex-battle build optimization with dice variance layered over every action.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Blackguards 2 leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Blackguards 2
Hex-grid turns carry no physical demand
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.
Blackguards 2
Enemy AI follows fixed tactical logic
Portal
No adversary modeling player.
Blackguards 2 leans clearly harder on variance.
Blackguards 2
Dark Eye dice rolls swing individual actions
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.
Blackguards 2
Build planning and battlefield manipulation are the deep solvable core
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.