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

Optimization · Pure Optimization
A hidden-object adventure about searching scenes and solving fixed puzzles.

Optimization · Pure Optimization
A fixed-solution puzzle adventure where finding the right inventory combination unlocks every obstacle.
Mystery Case Files: 13th Skull leans Optimization (Pure Optimization); The Secret of Monkey Island 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.
Mystery Case Files: 13th Skull
Pointing and clicking, no twitch demand
The Secret of Monkey Island
Clicking inventory items demands no twitch skill whatsoever
Mystery Case Files: 13th Skull leans a little harder on reads, though the gap is small.
Mystery Case Files: 13th Skull
No adaptive opponent, puzzles are fixed
The Secret of Monkey Island
No adaptive opponent; all puzzles are fixed and authored
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mystery Case Files: 13th Skull
Hidden-object locations unknown until searched
The Secret of Monkey Island
Some hidden items require exploration but solutions are invariant
The Secret of Monkey Island leans a little harder on optimization, though the gap is small.
Mystery Case Files: 13th Skull
Solving puzzles and finding objects is the whole loop
The Secret of Monkey Island
Correct item combinations and dialogue chains fully determine progress
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.