head to head
Neither is simply harder - they are hard in different places. Cult of the Lamb demands more variance; Portal 2 demands more optimization.

Optimization · Pure Optimization
A roguelite dungeon-crawler fused with a cult management sim.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Cult of the Lamb leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Cult of the Lamb leans a little harder on execution, though the gap is small.
Cult of the Lamb
Roguelite combat needs decent dodges.
Portal 2
Portal placement requires some precision but timing is lenient.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Cult of the Lamb
Enemies are scripted, not adaptive.
Portal 2
No opponent; puzzles are static.
Cult of the Lamb leans clearly harder on variance.
Cult of the Lamb
Run rooms and tarot pulls randomize.
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
Cult of the Lamb
Cult management and build synergies dominate.
Portal 2
Solving the puzzle's logic IS the entire game.
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.