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 · Light / Casual
A walking simulator piecing together a vanished English village's final days.

Optimization · Light / Casual
A first-person mystery about a fire lookout in a Wyoming forest.
Everybody's Gone to the Rapture leans Optimization (Light / Casual); Firewatch leans Optimization (Light / Casual).
Firewatch leans a little harder on execution, though the gap is small.
Everybody's Gone to the Rapture
Walking is the only verb
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.
Everybody's Gone to the Rapture
No opponent
Firewatch
No adaptive opposition.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Everybody's Gone to the Rapture
Story fragments hidden until found
Firewatch
Minor environmental discoveries.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Everybody's Gone to the Rapture
Light exploration completion at most
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.