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

Execution · Practiced Mastery
Twitch dodging and shooting layered over memorised arcade stage routes.

Execution · Practiced Mastery
Memorising scripted bullet waves and executing routes flawlessly for score.
Metal Slug leans Execution (Practiced Mastery); Raiden V: Director's Cut leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Slug
Dodging dense bullet patterns and precise shots carry every credit
Raiden V: Director's Cut
Weaving bullet patterns demands precise sustained piloting
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Slug
Enemies follow fixed arcade scripts, never adapt
Raiden V: Director's Cut
Enemy waves are fully scripted, nothing adapts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Slug
Spawns are nearly deterministic once a stage is learned
Raiden V: Director's Cut
Patterns are fixed; surprises vanish after one credit
Raiden V: Director's Cut leans a little harder on optimization, though the gap is small.
Metal Slug
One-credit clears come from memorising routes and spawn patterns
Raiden V: Director's Cut
Memorised routes and weapon choices define high scores
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.