head to head
vs
Gears of War 2vsHalf-Life Deathmatch: Source
Gears of War 2 leans Execution (Practiced Mastery); Half-Life Deathmatch: Source leans Execution (Pure Mechanics).
Gears of War 2Half-Life Deathmatch: Source
Axis by axis
Execution7 vs 8
Half-Life Deathmatch: Source leans harder on execution: Aim, bunny-hopping and snap reactions decide duels
Reads4 vs 4
Even - both lean on reads about the same.
Variance2 vs 1
Gears of War 2 leans harder on variance: Horde spawns add mild randomness
Optimization5 vs 4
Gears of War 2 leans harder on optimization: Power-weapon timing and positioning 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.