head to head
Micro Machines V3 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
Tests twitchy miniature car control and track memory amid party-weapon chaos.
Half-Life 2 leans Execution (Pure Mechanics); Micro Machines V3 leans Execution (Pure Mechanics).
Micro Machines V3 leans a little harder on execution, though the gap is small.
Half-Life 2
Gravity gun and shooting demand precision.
Micro Machines V3
Tiny cars on twisty tabletops punish every slip
Micro Machines V3 leans clearly harder on reads.
Half-Life 2
Combine AI scripted, non-adaptive.
Micro Machines V3
Couch rivals can be baited with weapons and nudges
Micro Machines V3 leans clearly harder on variance.
Half-Life 2
Almost no randomness.
Micro Machines V3
Pickup spawns and chaos shuffle close races
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.
Micro Machines V3
Track memorisation and shortcut lines pay off
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.