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 · Pure Mechanics
A light-gun shooting gallery testing aim and reaction speed.

Execution · Pure Mechanics
A run-and-gun arcade shooter that is almost pure twitch execution.
Gangster Town leans Execution (Pure Mechanics); Metal Slug 5 leans Execution (Pure Mechanics).
Metal Slug 5 leans a little harder on execution, though the gap is small.
Gangster Town
Aiming and fast shooting at targets decides everything
Metal Slug 5
precise dodge/shoot run-and-gun demands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Gangster Town
Enemies pop up on scripted cues, not adapting
Metal Slug 5
enemy waves are fully scripted patterns
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Gangster Town
Enemy appearance timing adds minor surprise
Metal Slug 5
minor drop and spawn randomness
Metal Slug 5 leans a little harder on optimization, though the gap is small.
Gangster Town
Little to solve beyond shooting accurately
Metal Slug 5
weapon pickup and route memorization
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.