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

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

Execution · Practiced Mastery
Memorising spawn patterns then executing them flawlessly under one-hit-death rules.
Grand Theft Auto V leans Execution (Practiced Mastery); Super Contra leans Execution (Practiced Mastery).
Super Contra leans clearly harder on execution.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Super Contra
One-hit deaths demand precise dodging and constant accurate fire
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Super Contra
Alien waves follow fixed spawn scripts
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Super Contra
Nothing random once spawn patterns are memorised
Super Contra leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Super Contra
Memorising spawns and weapon routes is half the run
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.