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.

Execution · Practiced Mastery
A monochrome puzzle-platformer about a boy lost in limbo.

Optimization · Practiced Mastery
A minimalist puzzle platformer about cooperating rectangles, carried by warm narration.
Limbo leans Execution (Practiced Mastery); Thomas Was Alone leans Optimization (Practiced Mastery).
Limbo leans a little harder on execution, though the gap is small.
Limbo
Tight platforming with trial-and-error.
Thomas Was Alone
Light precision jumps per quadrilateral
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Limbo
Hazards are scripted.
Thomas Was Alone
No opponent, narrated rectangles
Limbo leans a little harder on variance, though the gap is small.
Limbo
No randomness.
Thomas Was Alone
Levels fully visible and fixed
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Limbo
Puzzles have fixed solutions.
Thomas Was Alone
Sequencing each character's ability per puzzle
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.