head to head
Hitman 2 asks more than Portal, and the gap is variance.

Optimization · Pure Optimization
More sandbox murder puzzles with routing as the core skill.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Hitman 2 leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans a little harder on execution, though the gap is small.
Hitman 2
Light input demands at action moments.
Portal
Portal placement timing modest.
Hitman 2 leans a little harder on reads, though the gap is small.
Hitman 2
NPCs follow fixed routines.
Portal
No adversary modeling player.
Hitman 2 leans clearly harder on variance.
Hitman 2
Minor patrol and disguise randomness.
Portal
Deterministic chambers; no randomness.
Hitman 2 leans a little harder on optimization, though the gap is small.
Hitman 2
Each map a routing optimization problem.
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.