head to head
Kick Off 2 asks more than Half-Life 2, and the gap is reads.

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

Execution · Pure Mechanics
Famously unforgiving ball control tested against human prediction in fast matches.
Half-Life 2 leans Execution (Pure Mechanics); Kick Off 2 leans Execution (Pure Mechanics).
Kick Off 2 leans clearly harder on execution.
Half-Life 2
Gravity gun and shooting demand precision.
Kick Off 2
The ball never sticks - constant trapping demands famously precise control
Kick Off 2 leans clearly harder on reads.
Half-Life 2
Combine AI scripted, non-adaptive.
Kick Off 2
Human matches reward predicting passes and tackle timing
Kick Off 2 leans a little harder on variance, though the gap is small.
Half-Life 2
Almost no randomness.
Kick Off 2
Pitch types and deflections add mild chaos
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Half-Life 2
Linear progression with no builds.
Kick Off 2
Set plays and formation knowledge sit underneath
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.