diff --git a/engine/match.go b/engine/match.go
index c174a89..871b71b 100644
--- a/engine/match.go
+++ b/engine/match.go
@@ -364,7 +364,7 @@ func (mr *MatchRunner) generateMap(gs *GameState, numPlayers int) {
 
 	var primaryRadius, secondaryRadius float64
 	if numPlayers == 2 {
-		primaryRadius = 0.25   // ~10 tiles from center on 40x40 grid (~20 tiles apart) per plan §3.7.1
+		primaryRadius = 0.15   // ~6.8 tiles from center on 40x40 grid (~13.6 tiles apart)
 		secondaryRadius = 0.05 // ~2 tiles from center (closer to center for additional cores)
 	} else {
 		primaryRadius = 0.10 // ~5 tiles from center on 50x50 grid
diff --git a/engine/turn.go b/engine/turn.go
index c24619b..72efef1 100644
--- a/engine/turn.go
+++ b/engine/turn.go
@@ -204,9 +204,9 @@ func (gs *GameState) updateZoneRadiusToContainBots() {
 	}
 
 	// Set zone radius to contain all bots plus margin
-	// Margin is small to force bots together quickly before they can spread out
+	// Margin gives bots time to reach each other before zone kills them
 	maxDist := int(sqrt(maxDist2))
-	gs.ZoneRadius = maxDist + 5 // Margin gives bots time to reach each other before zone kills
+	gs.ZoneRadius = maxDist + 5 // Smaller margin to reach each other before zone kills
 }
 
 // sqrt returns the integer square root of n.
diff --git a/engine/types.go b/engine/types.go
index ad128c0..08e4898 100644
--- a/engine/types.go
+++ b/engine/types.go
@@ -193,7 +193,7 @@ func DefaultConfig() Config {
 		ZoneEnabled:        true,
 		ZoneStartTurn:      10, // Start early to force combat before passive bots spread
 		ZoneShrinkInterval: 1,  // Per plan §3.7.1 (both 2-player and 3+)
-		ZoneShrinkStep:     2,  // Per plan §3.7.1 (both 2-player and 3+)
+		ZoneShrinkStep:     1,  // Zone shrinks at same rate as bot movement (1 tile/turn)
 		ZoneMinRadius:      1,  // Per plan §3.7.1: 3+ player default (ConfigForPlayers overrides for 2-player)
 	}
 }
@@ -240,15 +240,15 @@ func ConfigForPlayers(numPlayers, coresPerPlayer int) Config {
 	// Zone diameter must be <= 2 * attack radius so bots at opposite zone edges can reach each other
 	// Target: 65-80% combat density per plan §3.7.1
 	if numPlayers == 2 {
-		cfg.ZoneStartTurn = 10     // Start early to force combat before passive bots spread (testing showed turn 10 too late)
+		cfg.ZoneStartTurn = 10      // Start early to force combat before random bots spread out
 		cfg.ZoneShrinkInterval = 1 // Per plan §3.7.1
-		cfg.ZoneShrinkStep = 2     // Per plan §3.7.1: 2 tiles per step forces engagement
+		cfg.ZoneShrinkStep = 1     // Zone shrinks at same rate as bot movement (1 tile/turn)
 		cfg.ZoneMinRadius = 2      // Per plan §3.7.1: 2-player min radius
 		cfg.AttackRadius2 = 25     // 5 tiles (reduced from 6 to achieve 65-80% combat density target)
 	} else {
-		cfg.ZoneStartTurn = 10     // Start early to force combat before passive bots spread
+		cfg.ZoneStartTurn = 10      // Start early to force combat before passive bots spread
 		cfg.ZoneShrinkInterval = 1 // Per plan §3.7.1
-		cfg.ZoneShrinkStep = 2     // Per plan §3.7.1: 2 tiles per step forces engagement
+		cfg.ZoneShrinkStep = 1     // Zone shrinks at same rate as bot movement (1 tile/turn)
 		cfg.ZoneMinRadius = 1      // Zone diameter (2) < attack radius (3.5), forces contact
 		cfg.AttackRadius2 = 12     // 3.5 tiles per plan §3.4 (3+ player)
 	}