Add rule for multiplying gold picked up.

Rules/README.md

@@ -12,6 +12,7 @@ RulesAPI.
 - **AbilityDamageAdjustedRule**: Ability damage is adjusted
 - **ActionPointsAdjustedRule**: Action points are adjusted
 - **EnemyRespawnDisabledRule**: Enemy respawns are disabled
+- **GoldPickedUpMultipliedRule**: Gold picked up is multiplied
 - **PieceConfigAdjustedRule**: Piece configuration is adjusted
   - See [PieceConfig.md](../docs/PieceConfig.md) for information about modifiable fields.
 - **RatNestsSpawnGoldRule**: Rat nests spawn gold

Rules/Rule/GoldPickedUpMultipliedRule.cs

@@ -0,0 +1,42 @@
+namespace Rules.Rule
+{
+    using Boardgame.Data;
+    using Boardgame.SerializableEvents;
+    using HarmonyLib;
+
+    public sealed class GoldPickedUpMultipliedRule : RulesAPI.Rule
+    {
+        public override string Description => "Gold picked up is multiplied";
+
+        private static double _multiplier;
+        private static bool _isActivated;
+
+        public GoldPickedUpMultipliedRule(double multiplier)
+        {
+            _multiplier = multiplier;
+        }
+
+        protected override void OnActivate() => _isActivated = true;
+
+        protected override void OnDeactivate() => _isActivated = false;
+
+        private static void OnPatch(Harmony harmony)
+        {
+            harmony.Patch(
+                original: AccessTools.Constructor(
+                    typeof(SerializableEventPickup),
+                    new[] { typeof(int), typeof(IntPoint2D), typeof(bool) }),
+                postfix: new HarmonyMethod(typeof(GoldPickedUpMultipliedRule), nameof(SerializableEventPickup_Constructor_Postfix)));
+        }
+
+        private static void SerializableEventPickup_Constructor_Postfix(ref SerializableEventPickup __instance)
+        {
+            if (!_isActivated)
+            {
+                return;
+            }
+
+            __instance.goldAmount = (int)(__instance.goldAmount * _multiplier);
+        }
+    }
+}

Rules/Rules.csproj

@@ -37,6 +37,7 @@
         <Compile Include="Rule\AbilityDamageAdjustedRule.cs" />
         <Compile Include="Rule\ActionPointsAdjustedRule.cs" />
         <Compile Include="Rule\EnemyRespawnDisabledRule.cs" />
+        <Compile Include="Rule\GoldPickedUpMultipliedRule.cs" />
         <Compile Include="Rule\RatNestsSpawnGoldRule.cs" />
         <Compile Include="Rule\SampleRule.cs" />
         <Compile Include="Rule\PieceConfigAdjustedRule.cs" />

Rules/RulesMod.cs

@@ -20,6 +20,7 @@ private static void RegisterNewRuleTypes()
             registrar.Register(typeof(Rule.AbilityDamageAdjustedRule));
             registrar.Register(typeof(Rule.ActionPointsAdjustedRule));
             registrar.Register(typeof(Rule.EnemyRespawnDisabledRule));
+            registrar.Register(typeof(Rule.GoldPickedUpMultipliedRule));
             registrar.Register(typeof(Rule.PieceConfigAdjustedRule));
             registrar.Register(typeof(Rule.RatNestsSpawnGoldRule));
             registrar.Register(typeof(Rule.StartHealthAdjustedRule));