head to head
Orcs Must Die! Unchained asks more than Grand Theft Auto: San Andreas, and the gap is reads.

Optimization · Practiced Mastery
A sprawling open-world crime epic with RPG-style character stats across a whole state.

Optimization · Practiced Mastery
Trap-maze economics against human attackers who adapt their pushes.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Orcs Must Die! Unchained leans Optimization (Practiced Mastery).
Orcs Must Die! Unchained leans a little harder on execution, though the gap is small.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Orcs Must Die! Unchained
Third-person combat matters but traps do the killing
Orcs Must Die! Unchained leans clearly harder on reads.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Orcs Must Die! Unchained
PvP sieges reward predicting enemy pushes and trap placement
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
Orcs Must Die! Unchained
Card draws and minion waves add mild noise
Orcs Must Die! Unchained leans a little harder on optimization, though the gap is small.
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
Orcs Must Die! Unchained
Trap economy and maze layout theory decide fortresses
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.