head to head
Neither is simply harder - they are hard in different places. Duke Nukem 3D demands more execution; Grand Theft Auto V demands more reads.

Execution · Practiced Mastery
A fast shooter that rewards learning enemy ambush patterns and hunting interactable environments for secrets and shortcuts.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Duke Nukem 3D leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Duke Nukem 3D leans clearly harder on execution.
Duke Nukem 3D
Fast movement and precise shooting across interactive environments
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Duke Nukem 3D
All enemies follow scripted AI; no adaptive opponent present
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Duke Nukem 3D leans a little harder on variance, though the gap is small.
Duke Nukem 3D
Enemy ambushes and secret placement are hidden on first run
Grand Theft Auto V
Some mission and lobby randomness.
Duke Nukem 3D leans a little harder on optimization, though the gap is small.
Duke Nukem 3D
Level structure and secret routing reward systematic exploration
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.