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

Optimization · Practiced Mastery
Routing scripted patrols with vampire teleports and a light skill-build layer.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Dark leans Optimization (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Grand Theft Auto V leans a little harder on execution, though the gap is small.
Dark
Shadow-teleport timing matters but combat is clunky-forgiving
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Dark
Guards run scripted patrol and alert routines
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Dark
Patrols are fixed once observed
Grand Theft Auto V
Some mission and lobby randomness.
Dark leans clearly harder on optimization.
Dark
Skill builds and patrol routing solve each stealth arena
Grand Theft Auto V
Heists, money loops, builds learnable.
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.