head to head
Neither is simply harder - they are hard in different places. Master of Orion (2016) demands more variance; Portal 2 demands more execution.

Optimization · Pure Optimization
Optimizing custom race design and tech priorities across a randomly generated galaxy.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Master of Orion (2016) leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Master of Orion (2016)
Turn-based menus; no physical demands at all
Portal 2
Portal placement requires some precision but timing is lenient.
Master of Orion (2016) leans clearly harder on reads.
Master of Orion (2016)
AI races follow defined personalities without adapting to your play
Portal 2
No opponent; puzzles are static.
Master of Orion (2016) leans clearly harder on variance.
Master of Orion (2016)
Random galaxy generation and diplomatic outcomes add hidden elements
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.
Master of Orion (2016)
Race design, tech priorities, and fleet composition are the solvable core
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.