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

Optimization · Pure Optimization
Solving fixed gravity-bending puzzles inside a deterministic nightmare.

Optimization · Pure Optimization
Linear JRPG built around real-time paradigm switching and stagger combat.
Darq leans Optimization (Pure Optimization); Final Fantasy XIII leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Darq
Slow stealth walking; minimal timing demands
Final Fantasy XIII
Paradigm shifts need timely menu reactions
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Darq
Nightmare enemies patrol fixed scripted routes
Final Fantasy XIII
Scripted stagger-phase bosses
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Darq
Puzzle solutions hidden only until first discovery
Final Fantasy XIII
Minor randomness in enemy actions
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Darq
Gravity-bending puzzle logic is the entire test
Final Fantasy XIII
Paradigm sequencing and stagger timing are solvable
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.