diff --git a/half-earth/resources/overlays/no_overlay.tres b/half-earth/resources/overlays/no_overlay.tres
index d4a783f..5f79807 100644
--- a/half-earth/resources/overlays/no_overlay.tres
+++ b/half-earth/resources/overlays/no_overlay.tres
@@ -4,3 +4,5 @@
 
 [resource]
 script = ExtResource( 1 )
+_healthy = Color( 0.0431373, 0.541176, 0.0235294, 1 )
+_depleted = Color( 0.670588, 0.572549, 0.27451, 1 )
diff --git a/half-earth/resources/tiles/tile_types/developed.tres b/half-earth/resources/tiles/tile_types/developed.tres
index 8f5f1d1..d9ffdac 100644
--- a/half-earth/resources/tiles/tile_types/developed.tres
+++ b/half-earth/resources/tiles/tile_types/developed.tres
@@ -7,4 +7,4 @@ script = ExtResource( 1 )
 Name = "Developed"
 Key = 68
 Color = Color( 0.372549, 0.372549, 0.372549, 1 )
-HeatGeneration = 0.4
+HeatGeneration = 0.15
diff --git a/half-earth/resources/tiles/tile_types/wild.tres b/half-earth/resources/tiles/tile_types/wild.tres
index 370bb83..20cc915 100644
--- a/half-earth/resources/tiles/tile_types/wild.tres
+++ b/half-earth/resources/tiles/tile_types/wild.tres
@@ -1,10 +1,11 @@
 [gd_resource type="Resource" load_steps=2 format=2]
 
-[ext_resource path="res://scripts/tile/TileType.cs" type="Script" id=1]
+[ext_resource path="res://scripts/tile/Wild.cs" type="Script" id=1]
 
 [resource]
 script = ExtResource( 1 )
 Name = "Wild"
 Key = 87
-Color = Color( 0, 0.545098, 0.0196078, 1 )
-HeatGeneration = -0.2
+Color = Color( 0.14902, 1, 0, 0 )
+HeatGeneration = -0.02
+Threshold = 0.6
diff --git a/half-earth/scripts/WorldGrid.cs b/half-earth/scripts/WorldGrid.cs
index 6a7b01a..83c546e 100644
--- a/half-earth/scripts/WorldGrid.cs
+++ b/half-earth/scripts/WorldGrid.cs
@@ -96,7 +96,7 @@ public class WorldGrid : Node2D
 
             TileView view = default;
             view.material = (ShaderMaterial)canvasItem.Material;
-            view.material.SetShaderParam("lowColor", _tileGrid.StartTileType.Color);
+            //view.material.SetShaderParam("lowColor", _tileGrid.StartTileType.Color);
             _tileViews[i] = view;
         }
     }
@@ -129,6 +129,20 @@ public class WorldGrid : Node2D
         py = y < _tileGrid.Size - 1 ? _tileGrid[x, y + 1].temperature : t;
     }
 
+    private void ApplyHeatDamage(ref Tile tile)
+    {
+        if (!(tile.type is IDamageable damageable))
+            return;
+
+        var surplus = tile.temperature - damageable.Threshold;
+        if (surplus < 0)
+            return;
+
+        // TODO: parameterised balancing
+        tile.currentHealth -= surplus;
+        tile.currentHealth = Mathf.Clamp(tile.currentHealth, 0, 1);
+    }
+
     private void GenerateHeat()
     {
         for (int i = 0; i < _tileGrid.Count; i++)
@@ -136,6 +150,7 @@ public class WorldGrid : Node2D
             var tile = _tileGrid[i];
             var type = tile.type;
             tile.temperature += type.HeatGeneration;
+            ApplyHeatDamage(ref tile);
             _tileGrid[i] = tile;
         }
     }
diff --git a/half-earth/scripts/overlays/NoOverlay.cs b/half-earth/scripts/overlays/NoOverlay.cs
index 49f8b1b..1222cec 100644
--- a/half-earth/scripts/overlays/NoOverlay.cs
+++ b/half-earth/scripts/overlays/NoOverlay.cs
@@ -2,10 +2,25 @@ using Godot;
 
 public class NoOverlay : Overlay
 {
+    [Export]
+    private Color _healthy;
+
+    [Export]
+    private Color _depleted;
+
     // in this view we want to draw tiles with their normal colour
     public override void Apply(Tile tile, ShaderMaterial material)
     {
         var type = tile.type;
+
+        if (type is Wild wild)
+        {
+            material.SetShaderParam("lowColor", _depleted);
+            material.SetShaderParam("highColor", _healthy);
+            material.SetShaderParam("t", tile.currentHealth);
+            return;
+        }
+
         material.SetShaderParam("lowColor", type.Color);
         material.SetShaderParam("t", 0);
     }
diff --git a/half-earth/scripts/tile/IDamageable.cs b/half-earth/scripts/tile/IDamageable.cs
new file mode 100644
index 0000000..6279a0d
--- /dev/null
+++ b/half-earth/scripts/tile/IDamageable.cs
@@ -0,0 +1,4 @@
+public interface IDamageable
+{
+    float Threshold { get; }
+}
\ No newline at end of file
diff --git a/half-earth/scripts/tile/Tile.cs b/half-earth/scripts/tile/Tile.cs
index 662c72c..3a51b55 100644
--- a/half-earth/scripts/tile/Tile.cs
+++ b/half-earth/scripts/tile/Tile.cs
@@ -5,4 +5,5 @@ public struct Tile
     public bool isHighlighted;
     public float temperature;
     public TileType type;
+    public float currentHealth;
 }
\ No newline at end of file
diff --git a/half-earth/scripts/tile/TileGrid.cs b/half-earth/scripts/tile/TileGrid.cs
index 7a2eb08..ef2c812 100644
--- a/half-earth/scripts/tile/TileGrid.cs
+++ b/half-earth/scripts/tile/TileGrid.cs
@@ -10,7 +10,7 @@ public class TileGrid : Resource, IReadOnlyList<Tile>
 
     [Export]
     private Resource _startTileTypeResource;
-    public TileType StartTileType => (TileType)_startTileTypeResource;
+    private TileType StartTileType => (TileType)_startTileTypeResource;
 
     public int Count => Size * Size;
 
@@ -58,6 +58,7 @@ public class TileGrid : Resource, IReadOnlyList<Tile>
             tile.isHighlighted = false;
             tile.temperature = 0.0f;
             tile.type = StartTileType;
+            tile.currentHealth = 1.0f;
 
             tiles.Add(tile);
         }
diff --git a/half-earth/scripts/tile/Wild.cs b/half-earth/scripts/tile/Wild.cs
new file mode 100644
index 0000000..5cfef22
--- /dev/null
+++ b/half-earth/scripts/tile/Wild.cs
@@ -0,0 +1,7 @@
+using Godot;
+
+public class Wild : TileType, IDamageable
+{
+    [Export]
+    public float Threshold { get; private set; }
+}
\ No newline at end of file