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 dark adventure game about a suicidal woman granted immortality to hunt five psychopaths.
Mystery Case Files: 13th Skull leans Optimization (Pure Optimization); The Cat Lady 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 Cat Lady
Side-scrolling adventure controls require no dexterity
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 Cat Lady
The Parasites are story antagonists, not adaptive opponents
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 Cat Lady
Mild unknowns in puzzle solutions on a blind playthrough
Mystery Case Files: 13th Skull 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 Cat Lady
Adventure-game puzzles have fixed discoverable solutions
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.