head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Optimization · Light / Casual
A relaxed hidden-object game about spotting cats in detailed scenes.

Optimization · Light / Casual
A first-person mystery about a fire lookout in a Wyoming forest.
A Tower Full of Cats leans Optimization (Light / Casual); Firewatch leans Optimization (Light / Casual).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
A Tower Full of Cats
Clicking hidden cats has no timing pressure
Firewatch
Walking and radio dialogue only.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
A Tower Full of Cats
Solo - nothing to predict
Firewatch
No adaptive opposition.
A Tower Full of Cats leans a little harder on variance, though the gap is small.
A Tower Full of Cats
Cat locations unknown until found, mildly randomized feel
Firewatch
Minor environmental discoveries.
A Tower Full of Cats leans a little harder on optimization, though the gap is small.
A Tower Full of Cats
Systematic scanning speeds completion but trivial
Firewatch
Few systems to optimize.
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.