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 · Practiced Mastery
Rapture's plasmid-and-pistol shooter where ideology meets gunplay.

Execution · Practiced Mastery
A campy 16-bit run-and-gun about rescuing neighbors from B-movie monsters.
BioShock leans Execution (Practiced Mastery); Zombies Ate My Neighbors leans Execution (Practiced Mastery).
Zombies Ate My Neighbors leans a little harder on execution, though the gap is small.
BioShock
Shooting and plasmid timing required.
Zombies Ate My Neighbors
Dodging monsters while sniping with squirt guns
BioShock leans a little harder on reads, though the gap is small.
BioShock
Splicers scripted; behaviors fixed.
Zombies Ate My Neighbors
Monster movie AI is fully patterned
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
BioShock
Loot and splicer spawns randomized.
Zombies Ate My Neighbors
Victim placement varies slightly per level
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
BioShock
Tonics, plasmids, weapon upgrades solvable.
Zombies Ate My Neighbors
Weapon-versus-monster matchups and level routing
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.