head to head
Earth Defense Force asks more than Half-Life 2, and the gap is variance.

Execution · Pure Mechanics
A top-down shoot-em-up testing aim and dodging against scripted alien waves.

Execution · Pure Mechanics
Landmark FPS built on physics puzzles and tight gunplay.
Earth Defense Force leans Execution (Pure Mechanics); Half-Life 2 leans Execution (Pure Mechanics).
Earth Defense Force leans a little harder on execution, though the gap is small.
Earth Defense Force
Top-down shooting and dodging are the core demand
Half-Life 2
Gravity gun and shooting demand precision.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Earth Defense Force
Enemies are scripted waves, not adaptive
Half-Life 2
Combine AI scripted, non-adaptive.
Earth Defense Force leans clearly harder on variance.
Earth Defense Force
Enemy spawn patterns add some unpredictability
Half-Life 2
Almost no randomness.
Earth Defense Force leans a little harder on optimization, though the gap is small.
Earth Defense Force
Weapon management and positioning aid survival
Half-Life 2
Linear progression with no builds.
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.