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

Optimization · Pure Optimization
A zombie survival sim where long-term planning outweighs moment-to-moment skill.

Optimization · Pure Optimization
A colorful loot ARPG where theorycrafting builds beats anything your hands do.
Project Zomboid leans Optimization (Pure Optimization); Torchlight II leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Project Zomboid
Combat is deliberate; precision matters but is slow.
Torchlight II
Faster combat asks for dodging and skill timing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Project Zomboid
Zombies follow scripted behaviour; no adaptation.
Torchlight II
Enemies are scripted swarms, never adaptive
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Project Zomboid
Loot spawns and zombie distributions randomized.
Torchlight II
Loot rolls and random maps drive the chase
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Project Zomboid
Skill grinding, base setup, and routing define survival.
Torchlight II
Skill trees and gear synergies decide character power
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.