head to head
Alekhine's Gun asks more than Portal 2, and the gap is variance.

Optimization · Pure Optimization
A Hitman-style Cold War stealth game about a KGB assassin working sandboxed kill missions.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Alekhine's Gun leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Alekhine's Gun leans a little harder on execution, though the gap is small.
Alekhine's Gun
Timing takedowns matters less than planning them
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.
Alekhine's Gun
NPC routines are clockwork, never reactive learning
Portal 2
No opponent; puzzles are static.
Alekhine's Gun leans clearly harder on variance.
Alekhine's Gun
First visits hide patrol routines and disguise rules
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans a little harder on optimization, though the gap is small.
Alekhine's Gun
Mapping routines and disguises reduces missions to solved puzzles
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.