head to head
Quake asks more than Half-Life 2, and the gap is execution.

Execution · Pure Mechanics
Landmark FPS built on physics puzzles and tight gunplay.

Execution · Pure Mechanics
The original twitch FPS - movement tech and rockets define skill.
Half-Life 2 leans Execution (Pure Mechanics); Quake leans Execution (Pure Mechanics).
Quake leans clearly harder on execution.
Half-Life 2
Gravity gun and shooting demand precision.
Quake
Rocket aim and movement tech ceiling massive.
Quake leans clearly harder on reads.
Half-Life 2
Combine AI scripted, non-adaptive.
Quake
PvP duels involve real opponent modeling.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Half-Life 2
Almost no randomness.
Quake
Item timing deterministic once learned.
Quake leans a little harder on optimization, though the gap is small.
Half-Life 2
Linear progression with no builds.
Quake
Map control and item routes solvable.
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.