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.

Optimization · Systems & Chaos
Blizzard's mobile Diablo where loot RNG and paid gem systems drive character power.

Optimization · Pure Optimization
Optimizing pair-up chains and offspring builds to steamroll deterministically scripted maps.
Diablo Immortal leans Optimization (Systems & Chaos); Fire Emblem Fates leans Optimization (Pure Optimization).
Diablo Immortal leans a little harder on execution, though the gap is small.
Diablo Immortal
Touch-friendly combat with dodge timing
Fire Emblem Fates
Turn-based menu play; no hand-speed demands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo Immortal
PvP battlegrounds exist but gear usually decides
Fire Emblem Fates
AI follows scripted attack priorities, not player modeling
Diablo Immortal leans a little harder on variance, though the gap is small.
Diablo Immortal
Legendary gem and loot RNG, heavily monetized
Fire Emblem Fates
Dual-strike/guard procs and hit rates inject meaningful RNG
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Diablo Immortal
Resonance, paragon, set optimization dominate power
Fire Emblem Fates
Offspring seals, asset/flaw selection, and supports are deeply planned
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.