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

Execution · Pure Mechanics
Tests raw aim and movement speed in fast classic arena deathmatch.

Execution · Practiced Mastery
The console FPS landmark that introduced Master Chief and the ring world.
Half-Life Deathmatch: Source leans Execution (Pure Mechanics); Halo: Combat Evolved leans Execution (Practiced Mastery).
Half-Life Deathmatch: Source leans a little harder on execution, though the gap is small.
Half-Life Deathmatch: Source
Aim, bunny-hopping and snap reactions decide duels
Halo: Combat Evolved
Aim, grenade timing, and vehicle control
Half-Life Deathmatch: Source leans a little harder on reads, though the gap is small.
Half-Life Deathmatch: Source
Predicting human movement and spawn timing matters
Halo: Combat Evolved
Multiplayer duels reward reading humans
Halo: Combat Evolved leans a little harder on variance, though the gap is small.
Half-Life Deathmatch: Source
Fixed maps and item timers, little randomness
Halo: Combat Evolved
Covenant AI varies tactics slightly
Halo: Combat Evolved leans a little harder on optimization, though the gap is small.
Half-Life Deathmatch: Source
Weapon spawns and map control are learnable systems
Halo: Combat Evolved
Weapon sandbox knowledge and encounter routing
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.