head to head
Iron Lung asks more than Firewatch, and the gap is variance.

Optimization · Light / Casual
A first-person mystery about a fire lookout in a Wyoming forest.

Variance · Light / Casual
Claustrophobic horror short about piloting a blind submarine through a blood ocean.
Firewatch leans Optimization (Light / Casual); Iron Lung leans Variance (Light / Casual).
Iron Lung leans a little harder on execution, though the gap is small.
Firewatch
Walking and radio dialogue only.
Iron Lung
Slow submarine piloting by coordinates
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.
Iron Lung
The thing outside follows a script
Iron Lung leans clearly harder on variance.
Firewatch
Minor environmental discoveries.
Iron Lung
Blind navigation; you see only camera snapshots
Iron Lung leans a little harder on optimization, though the gap is small.
Firewatch
Few systems to optimize.
Iron Lung
Plotting waypoints on the paper map
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.