head to head
Neither is simply harder - they are hard in different places. Boom Beach demands more variance; Portal 2 demands more execution.

Optimization · Pure Optimization
A base-layout and attack-planning puzzle against static player defenses.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Boom Beach leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Boom Beach
Tapping troop deployments takes no dexterity
Portal 2
Portal placement requires some precision but timing is lenient.
Boom Beach leans clearly harder on reads.
Boom Beach
Attacks hit static bases - defenders aren't present to adapt
Portal 2
No opponent; puzzles are static.
Boom Beach leans clearly harder on variance.
Boom Beach
Scouting reveals most info; matchmaking adds some spread
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans clearly harder on optimization.
Boom Beach
Base layouts, troop compositions and timing 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.