head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

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

Execution · Pure Mechanics
Rotary-stick aim and dodge execution through memorisable time-travel arenas.
Half-Life 2 leans Execution (Pure Mechanics); Time Soldiers leans Execution (Pure Mechanics).
Time Soldiers leans a little harder on execution, though the gap is small.
Half-Life 2
Gravity gun and shooting demand precision.
Time Soldiers
Rotary aiming while dodging in all directions is the test
Half-Life 2 leans a little harder on reads, though the gap is small.
Half-Life 2
Combine AI scripted, non-adaptive.
Time Soldiers
Era enemies and bosses are fixed arcade patterns
Time Soldiers leans a little harder on variance, though the gap is small.
Half-Life 2
Almost no randomness.
Time Soldiers
Time-period order shifts slightly between credits
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.
Time Soldiers
Power-up management and boss knowledge help modestly
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.