head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
Precision sniping and arena navigation through fixed, gimmick-laden levels.

Execution · Practiced Mastery
A destructible-environment FPS relying mainly on shooting execution.
MDK leans Execution (Practiced Mastery); Red Faction II 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.
MDK
Sniper-mode precision and arena dodging demand steady hands
Red Faction II
FPS aim and movement against enemies
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
MDK
Alien enemies behave on fixed scripts
Red Faction II
enemy soldiers use scripted AI behavior
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
MDK
Levels are authored with nothing random
Red Faction II
minor spawn and damage randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
MDK
Learning arena gimmicks and item use solves each level
Red Faction II
weapon choice and level routing
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.