Added some summaries

Interfaces/IDamageable.cs

@@ -1,10 +1,17 @@
+using UnityEngine;
+
 namespace GameDev.CoreSystems
 {
     public interface IDamageable
     {
         #region Methods
 
-        public void ModifyHealth(int healthChange);
+        /// <summary>
+        /// Modify the health of the damageable
+        /// </summary>
+        /// <param name="healthChange">Amount of health change</param>
+        /// <param name="source">Source GameObject, used to modify stats of the source. Total kills, etc.</param>
+        public void ModifyHealth(int healthChange, GameObject source);
 
         #endregion
 

Interfaces/IWeapon.cs

@@ -2,7 +2,13 @@ namespace GameDev.CoreSystems
 {
     public interface IWeapon
     {
+        /// <summary>
+        /// [s] Fire rate of the weapon
+        /// </summary>
         public float FireRate { get; set; }
+        /// <summary>
+        /// Weapon damage
+        /// </summary>
         public int Damage { get; set; }
     }
 }

Scripts/Damageable.cs

@@ -17,6 +17,11 @@ namespace GameDev.CoreSystems
 
         public UnityEvent DeathEvent;
 
+        /// <summary>
+        /// Used to ensure only one damage dealer gets the kill score  
+        /// </summary>
+        private bool _isAlreadyDead;
+
         private void OnEnable()
         {
             _activeDamageableRuntimeSet.Add(this);
@@ -29,13 +34,30 @@ namespace GameDev.CoreSystems
 
         #region Methods
 
-        public void ModifyHealth(int healthChange)
+        public void ModifyHealth(int healthChange, GameObject source)
         {
-            if (IsInvulnerable) return;
+            var receivingDamage = healthChange < 0;
+            var receivingHealing = healthChange > 0;
+
+            if (IsInvulnerable && receivingDamage) return;
 
             CurrentHealth += healthChange;
 
-            if (CurrentHealth >= 0) return;
+            source.TryGetComponent(out Weapon weapon);
+
+            if (weapon != null && !_isAlreadyDead)
+            {
+                weapon.IncrementDamageDealt(-healthChange);
+            }
+
+            if (CurrentHealth > 0 || _isAlreadyDead) return;
+
+            _isAlreadyDead = true;
+
+            if (weapon != null)
+            {
+                weapon.IncrementKillCount();
+            }
 
             print($"{transform.parent.parent.name} died");
             DeathEvent.Invoke();

Scripts/Weapon.cs

@@ -26,7 +26,8 @@ namespace GameDev.CoreSystems
             {
                 _timeUntilFire -= Time.deltaTime;
 
-                if (!(_timeUntilFire <= 0)) return;
+                var reloading = _timeUntilFire > 0;
+                if (reloading) return;
 
                 var position = BarrelEndPoint.position;
                 var forward = BarrelEndPoint.forward;
@@ -36,12 +37,9 @@ namespace GameDev.CoreSystems
                 {
                     if (hitInfo.transform.TryGetComponent(out Targetable target))
                     {
-                        target.Damageable.DeathEvent.AddListener(IncrementKillCount);
                         Debug.DrawRay(position, forward * Vector3.Distance(position, target.GetCenterPosition()),
                             Color.red, 0.1f);
-                        target.Damageable.ModifyHealth(-Damage);
+                        target.Damageable.ModifyHealth(-Damage, gameObject);
-                        DamageDealt += Damage;
-                        target.Damageable.DeathEvent.RemoveListener(IncrementKillCount);
                     }
                 }
 
@@ -53,7 +51,12 @@ namespace GameDev.CoreSystems
             }
         }
 
-        private void IncrementKillCount()
+        public void IncrementDamageDealt(int damage)
+        {
+            DamageDealt += damage;
+        }
+
+        public void IncrementKillCount()
         {
             NumberOfKills += 1;
         }