head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Optimization · Pure Optimization
A scripted RPG where pattern-learning and pacifist routing carry you.

Optimization · Practiced Mastery
Remake of the original Yakuza following Kiryu's return to Kamurocho.
Undertale leans Optimization (Pure Optimization); Yakuza Kiwami leans Optimization (Practiced Mastery).
Yakuza Kiwami leans a little harder on execution, though the gap is small.
Undertale
Bullet-hell dodging in scripted patterns
Yakuza Kiwami
Brawling combos and dodges are forgiving but present.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Undertale
NPCs follow fixed dialogue trees, not adaptive
Yakuza Kiwami
Majima ambushes are scripted, not adaptive.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Undertale
Minimal randomness in encounters
Yakuza Kiwami
Minor randomness in encounters and minigames.
Undertale leans a little harder on optimization, though the gap is small.
Undertale
Learning fixed boss patterns and mercy routes wins
Yakuza Kiwami
Style upgrades, heat moves and gear are learnable systems.
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.