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
Mapping dungeons and engineering party builds against chartable threats.

Optimization · Pure Optimization
A surreal point-and-click puzzle game tracing a family's dark history across generations.
Etrian Odyssey Untold: The Millennium Girl leans Optimization (Pure Optimization); Rusty Lake: Roots 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.
Etrian Odyssey Untold: The Millennium Girl
Turn-based menus require no dexterity
Rusty Lake: Roots
Clicking hotspots; occasional timing, nothing demanding.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Etrian Odyssey Untold: The Millennium Girl
FOE patterns are scripted and chartable
Rusty Lake: Roots
Scripted surreal events, never adaptive.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Etrian Odyssey Untold: The Millennium Girl
Unknown floors and ambushes punish until mapped
Rusty Lake: Roots
Obtuse hidden logic is unknown until discovered; fully convergent.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Etrian Odyssey Untold: The Millennium Girl
Party builds, skill synergies and map routing dominate
Rusty Lake: Roots
Cracking fixed item-and-clue chains drives every scene.
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.