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

Optimization · Pure Optimization
Solving procedurally generated corporate heists through precise resource and power management under escalating alarms.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Invisible, Inc. leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Invisible, Inc.
Turn-based movement; no twitch demands whatsoever
Portal
Portal placement timing modest.
Invisible, Inc. leans a little harder on reads, though the gap is small.
Invisible, Inc.
Corporate guards patrol on scripted timers; no adaptive opponent
Portal
No adversary modeling player.
Invisible, Inc. leans clearly harder on variance.
Invisible, Inc.
Procedural floor layouts and alarm escalation add significant run variance
Portal
Deterministic chambers; no randomness.
Invisible, Inc. leans a little harder on optimization, though the gap is small.
Invisible, Inc.
Power allocation, agent pairing, and escape routing are the core puzzle
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.