head to head
Half-Life asks more than Grand Theft Auto: San Andreas, and the gap is execution.

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

Execution · Practiced Mastery
Landmark scripted FPS following Gordon Freeman through the Black Mesa disaster.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Half-Life leans Execution (Practiced Mastery).
Half-Life leans clearly harder on execution.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Half-Life
Combat aim and infamous platforming sections
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Half-Life
Marines flank by script, not by modelling you
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
Half-Life
Set pieces surprise only on first run
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
Half-Life
Resource routing and encounter knowledge for speedruns
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.