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
An open-world revenge tale where a new shapeshifter hunts Alex Mercer through plague-zoned New York.
BioShock leans Execution (Practiced Mastery); Prototype 2 leans Execution (Practiced Mastery).
Prototype 2 leans a little harder on execution, though the gap is small.
BioShock
Shooting and plasmid timing required.
Prototype 2
Power-swapping combat and traversal demand decent dexterity
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
BioShock
Splicers scripted; behaviors fixed.
Prototype 2
Blackwatch and infected never adapt
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.
Prototype 2
Sandbox encounters carry slight randomness
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.
Prototype 2
Mutation upgrades and target-hunting routes reward planning
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.