head to head
vs
XCOM: Enemy UnknownvsZero Sievert
XCOM: Enemy Unknown leans Optimization (Systems & Chaos); Zero Sievert leans Variance (Systems & Chaos).
XCOM: Enemy UnknownZero Sievert
Axis by axis
Execution3 vs 5
Zero Sievert leans harder on execution: Top-down gunfights reward aim and positioning
Reads1 vs 0
XCOM: Enemy Unknown leans harder on reads: Aliens follow scripted AI, never model your specific habits
Variance7 vs 7
Even - both lean on variance about the same.
Optimization8 vs 7
XCOM: Enemy Unknown leans harder on optimization: Squad composition, research order, and base economy are solvable
Two games can score the same on an axis and still test it in very different ways - read each rationale, not just the number.