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
Arcade run-and-gun testing crowd dodging and spawn memorisation.

Execution · Practiced Mastery
Brutal cyberpunk twin-stick shooter about dash management and skill respeccing.
Mercs leans Execution (Pure Mechanics); Ruiner leans Execution (Practiced Mastery).
Mercs leans a little harder on execution, though the gap is small.
Mercs
Run-and-gun crowd weaving at arcade pace is everything
Ruiner
Dash timing and twin-stick precision under heavy pressure.
Ruiner leans a little harder on reads, though the gap is small.
Mercs
Soldiers spawn on fixed scripts
Ruiner
Enemy waves are fixed patterns.
Ruiner leans a little harder on variance, though the gap is small.
Mercs
Spawn tables barely vary between credits
Ruiner
First-run unknowns in arena compositions.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mercs
Weapon pickups and route memorisation stretch each credit
Ruiner
Respeccable skill builds per arena are a solvable puzzle.
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.