head to head
Neither is simply harder - they are hard in different places. Chants of Sennaar demands more variance; Portal demands more execution.

Optimization · Pure Optimization
A linguistic deduction game where each tower language must be decoded through patient observation and hypothesis.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Chants of Sennaar leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Chants of Sennaar
Stealth sections require basic patience not twitch reflexes
Portal
Portal placement timing modest.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Chants of Sennaar
Tower inhabitants follow scripted roles with no adaptive AI
Portal
No adversary modeling player.
Chants of Sennaar leans clearly harder on variance.
Chants of Sennaar
Hidden glyph meanings require exploration to uncover
Portal
Deterministic chambers; no randomness.
Chants of Sennaar leans a little harder on optimization, though the gap is small.
Chants of Sennaar
Deciphering each language layer is a systematic closed deduction problem
Portal
Pure puzzle-solving optimization.
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.