head to head
Cossacks 3 asks more than Portal, and the gap is reads.

Optimization · Pure Optimization
A large-scale real-time strategy game about massive army economies in the 17th century.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Cossacks 3 leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans a little harder on execution, though the gap is small.
Cossacks 3
unit micromanagement under real-time pressure
Portal
Portal placement timing modest.
Cossacks 3 leans clearly harder on reads.
Cossacks 3
human opponents bluff builds and attacks
Portal
No adversary modeling player.
Cossacks 3 leans clearly harder on variance.
Cossacks 3
minor combat outcome randomness
Portal
Deterministic chambers; no randomness.
Cossacks 3 leans a little harder on optimization, though the gap is small.
Cossacks 3
massive army economy and tech optimization
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.