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.

Execution · Practiced Mastery
Zero awakens to lead a resistance in a harsh, rank-graded GBA action series debut.

Execution · Pure Mechanics
Faster, gorier sequel built around dismembering aggressive enemies before they swarm you.
Mega Man Zero leans Execution (Practiced Mastery); Ninja Gaiden Sigma 2 leans Execution (Pure Mechanics).
Ninja Gaiden Sigma 2 leans a little harder on execution, though the gap is small.
Mega Man Zero
Punishing GBA action with strict ranking on damage
Ninja Gaiden Sigma 2
Delimb-and-finish combat under constant projectile pressure stays brutal
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man Zero
All bosses are pattern-based
Ninja Gaiden Sigma 2
Aggressive enemy AI remains pattern-driven
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man Zero
Cyber-elf locations hidden at first
Ninja Gaiden Sigma 2
Fixed missions; little randomness across runs
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mega Man Zero
Rank system penalises elf use, rewarding optimised clean runs
Ninja Gaiden Sigma 2
Weapon matchups and essence routing reward system study
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.