head to head
Star Control 3 asks more than Grand Theft Auto V, and the gap is optimization.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.

Optimization · Practiced Mastery
A space-strategy adventure mixing ship combat with empire resource management.
Grand Theft Auto V leans Execution (Practiced Mastery); Star Control 3 leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Star Control 3
Ship melee combat needs decent aim and maneuvering
Star Control 3 leans a little harder on reads, though the gap is small.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Star Control 3
AI captains use fixed tactics; some PvP melee allows prediction
Star Control 3 leans clearly harder on variance.
Grand Theft Auto V
Some mission and lobby randomness.
Star Control 3
Exploration and resource discovery are scripted-but-unknown
Star Control 3 leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Star Control 3
Fleet building, colonization and resource management drive progress
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.