head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Parasite Eve II demands more optimization.

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

Optimization · Practiced Mastery
A survival horror RPG blending real-time gunplay with tight ammo and build management.
Grand Theft Auto V leans Execution (Practiced Mastery); Parasite Eve II leans Optimization (Practiced Mastery).
Grand Theft Auto V leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Parasite Eve II
Real-time aiming, dodging, and tank-control positioning.
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Parasite Eve II
Creatures attack on fixed patterns.
Parasite Eve II leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Parasite Eve II
Unknown encounters and item placement first run.
Parasite Eve II leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Parasite Eve II
Ammo economy, parasite energy builds, and routing reward planning.
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.