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 · Practiced Mastery
The sequel adding Horde mode to the campaign-plus-versus cover shooter formula.

Execution · Pure Mechanics
Tests precise steering on cramped miniature tracks where one slip means falling off the table.
Gears of War 2 leans Execution (Practiced Mastery); Micro Machines 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.
Gears of War 2
Gnasher battles and movement tech set the ceiling
Micro Machines
Tiny cars on twisty tabletop tracks demand constant precise steering
Gears of War 2 leans a little harder on reads, though the gap is small.
Gears of War 2
Human opponents in versus drive prediction play
Micro Machines
Local multiplayer screen-edge duels reward predicting rivals' lines
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Gears of War 2
Horde spawns add mild randomness
Micro Machines
Tracks are fixed; little randomness beyond AI bumping
Gears of War 2 leans a little harder on optimization, though the gap is small.
Gears of War 2
Power-weapon timing and positioning are solvable
Micro Machines
Learning each track's racing line and shortcuts pays 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.