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

Optimization · Pure Optimization
Bleak Ellison adaptation where five tortured souls face a sadistic AI.

Optimization · Pure Optimization
A LucasArts sci-fi adventure where astronauts stranded on an alien world puzzle out its dead civilization.
I Have No Mouth, and I Must Scream leans Optimization (Pure Optimization); The Dig leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
I Have No Mouth, and I Must Scream
Pure point-and-click, no dexterity
The Dig
Point-and-click; no reflex demands.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
I Have No Mouth, and I Must Scream
AM is scripted despite the menace
The Dig
Alien world is static; companions follow scripts.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
I Have No Mouth, and I Must Scream
Obscure solutions hidden until discovered
The Dig
Alien machinery's purpose is hidden until experimented with.
I Have No Mouth, and I Must Scream leans a little harder on optimization, though the gap is small.
I Have No Mouth, and I Must Scream
Puzzle chains and ethical-path knowledge
The Dig
Machine puzzles have single fixed solutions to deduce.
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.