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.

Optimization · Practiced Mastery
A tower defense FPS hybrid about placing defenses and gunning down waves.

Optimization · Pure Optimization
A tactical squad shooter where positioning and probability management outweigh raw aim.
Iron Grip: Warlord leans Optimization (Practiced Mastery); The Bureau: XCOM Declassified leans Optimization (Pure Optimization).
Iron Grip: Warlord leans a little harder on execution, though the gap is small.
Iron Grip: Warlord
First-person shooting demands some aim under pressure
The Bureau: XCOM Declassified
cover shooting timing is moderate
Iron Grip: Warlord leans a little harder on reads, though the gap is small.
Iron Grip: Warlord
AI invaders follow scripted waves, no adaptation
The Bureau: XCOM Declassified
alien AI is scripted, no adaptation
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Iron Grip: Warlord
Wave composition adds some uncertainty
The Bureau: XCOM Declassified
cover-based hit chances are randomized
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Iron Grip: Warlord
Tower placement and resource management defend the city
The Bureau: XCOM Declassified
squad tactics and builds 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.