head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Metroid Prime Remastered demands more optimization.

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

Execution · Practiced Mastery
A first-person exploration game where precise aim and route optimization both matter.
Grand Theft Auto V leans Execution (Practiced Mastery); Metroid Prime Remastered leans Execution (Practiced Mastery).
Metroid Prime Remastered leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Metroid Prime Remastered
FPS aiming and platforming precision
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Metroid Prime Remastered
bosses use fixed attack patterns
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Metroid Prime Remastered
minor drop/damage variance
Metroid Prime Remastered leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Metroid Prime Remastered
sequence breaking, item routing, upgrades
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.