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

Optimization · Pure Optimization
A dark-fantasy strategy RPG about building armies and winning turn-based battles.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.
Disciples: Liberation leans Optimization (Pure Optimization); Portal 2 leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Disciples: Liberation
Turn-based combat needs no input speed
Portal 2
Portal placement requires some precision but timing is lenient.
Disciples: Liberation leans clearly harder on reads.
Disciples: Liberation
AI uses fixed tactics; multiplayer adds light prediction
Portal 2
No opponent; puzzles are static.
Disciples: Liberation leans clearly harder on variance.
Disciples: Liberation
Damage rolls and map encounters carry randomness
Portal 2
Puzzles are deterministic with no randomness.
Portal 2 leans a little harder on optimization, though the gap is small.
Disciples: Liberation
Army composition, upgrades and tactical positioning decide battles
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.