diff --git a/src/simulator/crates/mc-city/src/city.rs b/src/simulator/crates/mc-city/src/city.rs
index d6edc15d..2bd20d0a 100644
--- a/src/simulator/crates/mc-city/src/city.rs
+++ b/src/simulator/crates/mc-city/src/city.rs
@@ -106,8 +106,11 @@ impl TileYield {
 /// with two decent food tiles. Target: median p0_pop_peak ≥ 7 at T150.
 pub const FOOD_PER_POP: f64 = 1.2;
 
-/// Base city HP before population scaling.
-pub const BASE_CITY_HP: u32 = 200;
+/// Base city HP before population scaling. Tuned up from 200 to extend TTV:
+/// prior batches showed capitals falling at T99/T116 because a pop-3 capital
+/// (230 HP) could be melted in ~15 siege turns even with walls. At 260 base,
+/// pop-3 walled capital = 290+50 = 340 HP, pushing capture to T200+.
+pub const BASE_CITY_HP: u32 = 260;
 
 /// HP gained per population point.
 pub const HP_PER_POP: u32 = 10;
@@ -511,10 +514,13 @@ impl City {
         self.hp = (self.hp + amount).min(self.max_hp);
     }
 
-    /// Heal the city by the standard per-turn amount (10 HP).
+    /// Heal the city by the standard per-turn amount (20 HP).
+    /// Raised from 10 to 20 to extend siege duration: at 10/turn regen a
+    /// 2-warrior assault could chain captures in ~15 turns, giving T99/T116
+    /// fast wins. 20/turn forces attackers to commit more force or siege.
     /// Skips destroyed cities (HP == 0).
     pub fn heal_per_turn(&mut self) {
-        const HEAL_PER_TURN: u32 = 10;
+        const HEAL_PER_TURN: u32 = 20;
         if self.hp > 0 && self.hp < self.max_hp {
             self.heal(HEAL_PER_TURN);
         }
diff --git a/src/simulator/crates/mc-combat/src/siege.rs b/src/simulator/crates/mc-combat/src/siege.rs
index de54f09d..7db55408 100644
--- a/src/simulator/crates/mc-combat/src/siege.rs
+++ b/src/simulator/crates/mc-combat/src/siege.rs
@@ -23,12 +23,13 @@ const RANGED_CITY_HP_FRACTION: f32 = 0.75;
 
 /// Compute the penalty multiplier for melee attacks against a walled city.
 /// Returns a value < 1.0 that the attacker's effective strength is multiplied by.
-/// Scales by tier: 0=1.0, 1=0.80 (walls), 2=0.65 (castle).
+/// Scales by tier: 0=1.0, 1=0.70 (walls), 2=0.55 (castle).
+/// Tightened from 0.80/0.65 to slow sieges after fast-win regressions (T99/T116).
 pub fn melee_wall_penalty(wall_tier: i32) -> f32 {
     match wall_tier {
         0 => 1.0,
-        1 => 0.80,
-        _ => 0.65,
+        1 => 0.70,
+        _ => 0.55,
     }
 }
 
@@ -90,9 +91,9 @@ mod tests {
     #[test]
     fn melee_penalty_scales_by_tier() {
         assert!((melee_wall_penalty(0) - 1.0).abs() < 0.001);
-        assert!((melee_wall_penalty(1) - 0.80).abs() < 0.001);
-        assert!((melee_wall_penalty(2) - 0.65).abs() < 0.001);
-        assert!((melee_wall_penalty(3) - 0.65).abs() < 0.001);
+        assert!((melee_wall_penalty(1) - 0.70).abs() < 0.001);
+        assert!((melee_wall_penalty(2) - 0.55).abs() < 0.001);
+        assert!((melee_wall_penalty(3) - 0.55).abs() < 0.001);
     }
 
     #[test]