head to head
T2: The Arcade Game 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
A rail-shooter endurance test of target tracking against memorised enemy waves.
Half-Life 2 leans Execution (Pure Mechanics); T2: The Arcade Game leans Execution (Pure Mechanics).
T2: The Arcade Game leans clearly harder on execution.
Half-Life 2
Gravity gun and shooting demand precision.
T2: The Arcade Game
Tracking dozens of targets with cursor speed is everything
Half-Life 2 leans a little harder on reads, though the gap is small.
Half-Life 2
Combine AI scripted, non-adaptive.
T2: The Arcade Game
Waves are choreographed, nothing adapts
T2: The Arcade Game leans a little harder on variance, though the gap is small.
Half-Life 2
Almost no randomness.
T2: The Arcade Game
Spawn details blur slightly but patterns dominate
T2: The Arcade Game leans a little harder on optimization, though the gap is small.
Half-Life 2
Linear progression with no builds.
T2: The Arcade Game
Learning wave order and powerup spots stretches credits
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.