head to head
Call of DutyvsKillzone: Mercenary
Call of Duty leans Execution (Practiced Mastery); Killzone: Mercenary leans Execution (Pure Mechanics).
Call of DutyKillzone: Mercenary
Axis by axis
Execution7 vs 7
Even - both lean on execution about the same.
Reads3 vs 4
Killzone: Mercenary leans harder on reads: Multiplayer rewards reading enemy rotations and habits
Variance2 vs 2
Even - both lean on variance about the same.
Optimization5 vs 4
Call of Duty leans harder on optimization: Memorising set pieces and weapon positions
Two games can score the same on an axis and still test it in very different ways - read each rationale, not just the number.

