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 · Pure Optimization
Stealth adventure about a minstrel mouse sneaking through a rat-run fortress.

Optimization · Practiced Mastery
Co-op superhero brawler about assembling the right four-hero squad and builds.
Ghost of a Tale leans Optimization (Pure Optimization); Marvel: Ultimate Alliance leans Optimization (Practiced Mastery).
Marvel: Ultimate Alliance leans a little harder on execution, though the gap is small.
Ghost of a Tale
Light sneak-and-dash timing
Marvel: Ultimate Alliance
brawling and dodge timing are forgiving
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Ghost of a Tale
Guard rats patrol fixed mappable routes
Marvel: Ultimate Alliance
enemies are scripted mobs
Ghost of a Tale leans a little harder on variance, though the gap is small.
Ghost of a Tale
Quest items and routes hidden first time
Marvel: Ultimate Alliance
some loot and unlock randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Ghost of a Tale
Costumes, routes, and quest-chain solutions
Marvel: Ultimate Alliance
team bonuses, gear, and skill builds carry difficulty
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.