head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Competitive PvP
An acrobatic online shooter about movement-heavy gunplay against humans.

Execution · Pure Mechanics
Trilogy capstone whose equal-start arena multiplayer defined a console generation.
GunZ 2: The Second Duel leans Execution (Competitive PvP); Halo 3 leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
GunZ 2: The Second Duel
Acrobatic movement and aim are the core skill ceiling
Halo 3
Precision aim and grenade-melee timing
GunZ 2: The Second Duel leans a little harder on reads, though the gap is small.
GunZ 2: The Second Duel
Against humans, predicting movement and fakes matters
Halo 3
Equal-start fights reward predicting humans
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
GunZ 2: The Second Duel
Minor weapon spread, mostly deterministic
Halo 3
Equipment pickups and spawn variation
Halo 3 leans a little harder on optimization, though the gap is small.
GunZ 2: The Second Duel
Class and loadout choices support but skill leads
Halo 3
Power-weapon timers and map control
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.