Building comparison
head to head
PortalvsUndertale
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.
Portal
Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Undertale
Optimization · Pure Optimization
A scripted RPG where pattern-learning and pacifist routing carry you.
Portal leans Optimization (Pure Optimization); Undertale leans Optimization (Pure Optimization).
PortalUndertale
Axis by axis
Execution4 vs 4
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
Portal placement timing modest.
Undertale
Bullet-hell dodging in scripted patterns
Reads0 vs 1
Undertale leans a little harder on reads, though the gap is small.
Portal
No adversary modeling player.
Undertale
NPCs follow fixed dialogue trees, not adaptive
Variance0 vs 1
Undertale leans a little harder on variance, though the gap is small.
Portal
Deterministic chambers; no randomness.
Undertale
Minimal randomness in encounters
Optimization8 vs 7
Portal leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
Undertale
Learning fixed boss patterns and mercy routes wins
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.