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

Execution · Practiced Mastery
A twin-stick looter shooter blending Housemarque arcade reflexes with a loot-grind build layer.

Execution · Practiced Mastery
Fan-built ground-up remake of Half-Life with a reimagined Xen.
Alienation leans Execution (Practiced Mastery); Black Mesa 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.
Alienation
Twin-stick aim and dodge under heavy swarm pressure.
Black Mesa
Classic FPS aim and platforming sequences
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Alienation
Alien hordes never adapt.
Black Mesa
Marines and aliens follow set scripts
Alienation leans a little harder on variance, though the gap is small.
Alienation
Random loot cores and weapon rolls.
Black Mesa
Minor enemy placement surprises first run
Black Mesa leans a little harder on optimization, though the gap is small.
Alienation
Build and core-socketing choices scale the endgame.
Black Mesa
Route, resource, and encounter knowledge
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.