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
Steady aim against scripted alien swarms with an upgrade economy underneath.

Execution · Practiced Mastery
A classic beat 'em up sequel where the Lee brothers avenge Marian with kicks and knees.
Alien Breed: Impact leans Execution (Practiced Mastery); Double Dragon II: The Revenge leans Execution (Practiced Mastery).
Double Dragon II: The Revenge leans a little harder on execution, though the gap is small.
Alien Breed: Impact
Kiting alien swarms top-down demands steady aim and movement
Double Dragon II: The Revenge
Directional attacks and knee timing carry every fight
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Alien Breed: Impact
Aliens swarm on scripts, never modelling you
Double Dragon II: The Revenge
Enemy thugs use fixed AI routines
Alien Breed: Impact leans a little harder on variance, though the gap is small.
Alien Breed: Impact
Ambush triggers are scripted-but-unknown first time through
Double Dragon II: The Revenge
Minor enemy positioning randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Alien Breed: Impact
Weapon upgrades and ammo economy reward planning
Double Dragon II: The Revenge
Learning stage layouts and abusing the hyper knee
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.