head to head
Orcs Must Die! asks more than Portal, and the gap is variance.

Optimization · Pure Optimization
A third-person tower defense about funneling orc hordes into gleefully lethal trap corridors.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Orcs Must Die! leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Orcs Must Die!
Active shooting supplements the traps
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.
Orcs Must Die!
Orc waves follow fixed paths
Portal
No adversary modeling player.
Orcs Must Die! leans clearly harder on variance.
Orcs Must Die!
Minor wave composition randomness
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.
Orcs Must Die!
Trap placement and kill-corridor economics are the game
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.