head to head
Halo 4 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.

Execution · Practiced Mastery
343's debut pits Master Chief against the Didact with loadout-driven multiplayer.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Halo 4 leans Execution (Practiced Mastery).
Halo 4 leans clearly harder on execution.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Halo 4
Precision aim amid faster kill times
Halo 4 leans clearly harder on reads.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Halo 4
Human opponents in Infinity multiplayer
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
Halo 4
Ordnance drops randomise mid-match rewards
Grand Theft Auto: San Andreas 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
Halo 4
Loadout building and map control
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.