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 first-person mystery about a fire lookout in a Wyoming forest.

Optimization · Light / Casual
An interactive novel that tests narrative attention more than any game skill.
Firewatch leans Optimization (Light / Casual); Ken Follett's The Pillars of the Earth 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.
Firewatch
Walking and radio dialogue only.
Ken Follett's The Pillars of the Earth
Point-and-click input has no physical ceiling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Firewatch
No adaptive opposition.
Ken Follett's The Pillars of the Earth
Branching story characters follow scripts, not minds
Ken Follett's The Pillars of the Earth leans a little harder on variance, though the gap is small.
Firewatch
Minor environmental discoveries.
Ken Follett's The Pillars of the Earth
Choice outcomes are unknown on a first playthrough
Ken Follett's The Pillars of the Earth leans a little harder on optimization, though the gap is small.
Firewatch
Few systems to optimize.
Ken Follett's The Pillars of the Earth
Puzzles are sparse and single-solution
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.