head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
Helicopter handling under fire while routing fuel and ammo across fixed missions.

Execution · Practiced Mastery
Landmark scripted FPS following Gordon Freeman through the Black Mesa disaster.
Desert Strike: Return to the Gulf leans Execution (Practiced Mastery); Half-Life leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Desert Strike: Return to the Gulf
Helicopter inertia and dodging fire demand real stick control
Half-Life
Combat aim and infamous platforming sections
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Desert Strike: Return to the Gulf
Defenses are fixed emplacements, nothing adapts
Half-Life
Marines flank by script, not by modelling you
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Desert Strike: Return to the Gulf
Maps are unknown on first sortie only
Half-Life
Set pieces surprise only on first run
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Desert Strike: Return to the Gulf
Fuel, ammo and mission-order routing is the strategic core
Half-Life
Resource routing and encounter knowledge for speedruns
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.