head to head
Portal 2 asks more than Hexcells, and the gap is execution.

Optimization · Pure Optimization
An elegant hex-grid logic puzzler that is always solvable by deduction alone, never guessing.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Hexcells leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Hexcells
Clicking hexes calmly; no physical test.
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.
Hexcells
No opponent exists.
Portal 2
No opponent; puzzles are static.
Hexcells leans a little harder on variance, though the gap is small.
Hexcells
Designed to need zero guessing; full information.
Portal 2
Puzzles are deterministic with no randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Hexcells
Minesweeper-style pure deduction is the entire game.
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.