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

Optimization · Pure Optimization
Factory-meets-tower-defense; belts feed your defenses.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Mindustry leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans a little harder on execution, though the gap is small.
Mindustry
some tower placement under pressure
Portal
Portal placement timing modest.
Mindustry leans a little harder on reads, though the gap is small.
Mindustry
scripted enemy waves
Portal
No adversary modeling player.
Mindustry leans clearly harder on variance.
Mindustry
map layout variation
Portal
Deterministic chambers; no randomness.
Mindustry leans clearly harder on optimization.
Mindustry
factory belts and logistics chains
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.