head to head
Neither is simply harder - they are hard in different places. Portal 2 demands more execution; We Were Here Together demands more variance.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.

Optimization · Pure Optimization
A two-player co-op escape adventure built on describing what only you can see over voice chat.
Portal 2 leans Optimization (Pure Optimization); We Were Here Together leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Portal 2
Portal placement requires some precision but timing is lenient.
We Were Here Together
Walking and interacting; minimal physical demand.
We Were Here Together leans a little harder on reads, though the gap is small.
Portal 2
No opponent; puzzles are static.
We Were Here Together
Partner is an ally; puzzles never adapt.
We Were Here Together leans clearly harder on variance.
Portal 2
Puzzles are deterministic with no randomness.
We Were Here Together
Asymmetric hidden information is the core mechanic.
Portal 2 leans a little harder on optimization, though the gap is small.
Portal 2
Solving the puzzle's logic IS the entire game.
We Were Here Together
Fixed symbol-and-mechanism puzzles, fully solvable once both sides known.
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.