head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Optimization · Pure Optimization
Bigger battlefields and war machines scale the trap-corridor formula to thousand-orc sieges.

Optimization · Pure Optimization
Side-on turn-based tactics where you manually aim ricocheting bullets for a steambot pirate crew.
Orcs Must Die! 3 leans Optimization (Pure Optimization); SteamWorld Heist 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! 3
War scenarios add active combat pressure
SteamWorld Heist
Manual aim and ricochet shots reward steady hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Orcs Must Die! 3
Fixed AI pathing, no adaptation
SteamWorld Heist
Enemy bots follow fixed behaviors
SteamWorld Heist leans a little harder on variance, though the gap is small.
Orcs Must Die! 3
Mission modifiers vary runs slightly
SteamWorld Heist
Procedural ship layouts and loot drops
Orcs Must Die! 3 leans a little harder on optimization, though the gap is small.
Orcs Must Die! 3
War machines and trap economics reward solved layouts
SteamWorld Heist
Crew builds, weapon picks, and turn routing carry runs
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.