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 relentless wave-clearing shooter that tests sustained aim and movement against massive scripted enemy crowds.

Execution · Pure Mechanics
Tests twin-stick reflexes and threat triage under relentless arcade pressure.
Painkiller (2004) leans Execution (Pure Mechanics); Super Stardust Ultra leans Execution (Pure Mechanics).
Super Stardust Ultra leans a little harder on execution, though the gap is small.
Painkiller (2004)
Constant crowd-control movement against overwhelming enemy counts demands fast aim
Super Stardust Ultra
Twin-stick dodging through dense asteroid fields is everything
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Painkiller (2004)
All enemies are scripted waves with fixed attack patterns
Super Stardust Ultra
Waves are spawned patterns, not adaptive opponents
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Painkiller (2004)
Enemy counts and placements are fixed with minimal unknown elements
Super Stardust Ultra
Spawn timing varies slightly but is quickly familiar
Painkiller (2004) leans a little harder on optimization, though the gap is small.
Painkiller (2004)
Tarot card selection and level routing provide a thin solvable layer
Super Stardust Ultra
Weapon choice and multiplier management refine 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.