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.

Optimization · Practiced Mastery
A chaotic co-op action game where wizards combine eight elements into thousands of spells, often frying each other.

Optimization · Practiced Mastery
A portable Metal Gear pairing mission stealth with a base-building development metagame.
Magicka leans Optimization (Practiced Mastery); Metal Gear Solid: Peace Walker leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Magicka
Typing element combos quickly mid-combat is the hands test
Metal Gear Solid: Peace Walker
Boss vehicle fights and CQC chains test aim and timing.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Magicka
Enemies are scripted; friendly fire isn't adaptive
Metal Gear Solid: Peace Walker
Enemy AI is scripted and predictable.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Magicka
Co-op friendly-fire chaos adds unpredictability
Metal Gear Solid: Peace Walker
Missions are fixed; soldier recruitment adds slight randomness.
Metal Gear Solid: Peace Walker leans a little harder on optimization, though the gap is small.
Magicka
Discovering and exploiting spell combinations dominates
Metal Gear Solid: Peace Walker
Mother Base management and weapon development are pure systems.
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.