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

Optimization · Pure Optimization
Tests squad-building and lane positioning in a tactics system that rewards deep planning.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Grand Kingdom leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Grand Kingdom
Timed inputs in battle are forgiving
Portal
Portal placement timing modest.
Grand Kingdom leans clearly harder on reads.
Grand Kingdom
Online war pits you against other players' AI-run squads
Portal
No adversary modeling player.
Grand Kingdom leans clearly harder on variance.
Grand Kingdom
Enemy squad compositions are hidden until engagement
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.
Grand Kingdom
Squad formation, positioning and gear are deeply 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.