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
Gravity-shifting action adventure about falling sideways through a floating city.

Execution · Practiced Mastery
Third-person action where Captain Titus chainswords through ork hordes without a cover system.
Gravity Rush leans Execution (Practiced Mastery); Warhammer 40,000: Space Marine leans Execution (Practiced Mastery).
Warhammer 40,000: Space Marine leans a little harder on execution, though the gap is small.
Gravity Rush
Aerial gravity-kick aiming takes spatial control
Warhammer 40,000: Space Marine
Melee-shooting flow and execution timing carry combat
Warhammer 40,000: Space Marine leans a little harder on reads, though the gap is small.
Gravity Rush
Nevi enemies are scripted
Warhammer 40,000: Space Marine
Ork hordes follow scripted aggression
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Gravity Rush
Authored world, minimal randomness
Warhammer 40,000: Space Marine
Encounters are fixed and predictable
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Gravity Rush
Gem farming and upgrade priorities
Warhammer 40,000: Space Marine
Weapon choice and fury management are simple to learn
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.