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

Execution · Practiced Mastery
Cave's genre-defining bullet hell where survival is execution and score is a memorized chain route.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
DoDonPachi leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
DoDonPachi leans clearly harder on execution.
DoDonPachi
Threading dense bullet curtains demands pixel-perfect movement
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
DoDonPachi
Fixed scripted patterns, nothing adapts
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.
DoDonPachi
Near-fully deterministic once patterns are learned
Grand Theft Auto V
Some mission and lobby randomness.
DoDonPachi leans clearly harder on optimization.
DoDonPachi
Chain meter routing defines high-level play entirely
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.