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

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

Execution · Practiced Mastery
A class-based action game demanding careful puzzle routing and resource management across an interconnected hub world.
Grand Theft Auto V leans Execution (Practiced Mastery); Hexen: Beyond Heretic leans Execution (Practiced Mastery).
Hexen: Beyond Heretic leans clearly harder on execution.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Hexen: Beyond Heretic
Class-specific weapons reward mastering unique attack timing and range
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Hexen: Beyond Heretic
Enemies are scripted; no adaptive opponent exists
Hexen: Beyond Heretic leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Hexen: Beyond Heretic
Puzzle item placement and key locations are opaque until found
Hexen: Beyond Heretic leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Hexen: Beyond Heretic
Hub-world puzzle routing and class selection form a solvable structure
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.