head to head
Neither is simply harder - they are hard in different places. Portal demands more execution; Tom Clancy's Ghost Recon: Shadow Wars demands more reads.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.

Optimization · Pure Optimization
A turn-based tactics game testing unit positioning and ability sequencing.
Portal leans Optimization (Pure Optimization); Tom Clancy's Ghost Recon: Shadow Wars leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
Tom Clancy's Ghost Recon: Shadow Wars
Selecting units on a grid demands no twitch
Tom Clancy's Ghost Recon: Shadow Wars leans clearly harder on reads.
Portal
No adversary modeling player.
Tom Clancy's Ghost Recon: Shadow Wars
AI follows turn-based tactical scripts, not adaptive prediction
Tom Clancy's Ghost Recon: Shadow Wars leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Tom Clancy's Ghost Recon: Shadow Wars
Hit chances add small randomness to combat
Tom Clancy's Ghost Recon: Shadow Wars leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
Tom Clancy's Ghost Recon: Shadow Wars
Positioning, ability synergy and turn planning is the game
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.