diff --git a/2015/Day-06/Day06.cs b/2015/Day-06/Day06.cs
new file mode 100644
index 0000000..b45f68d
--- /dev/null
+++ b/2015/Day-06/Day06.cs
@@ -0,0 +1,77 @@
+// Define a 2D array to hold the light values.
+bool[,] lights = new bool[1000,1000];
+int[,] brightness = new int[1000,1000];
+
+// Parse the instructions.
+foreach(string line in File.ReadLines("input.txt")){
+    string[] words = line.Split(' ');
+    string action = string.Empty;
+    string start = string.Empty;
+    string end = string.Empty;
+
+    switch(words[0]){
+        case "turn":
+            action = words[1];
+            start = words[2];
+            end = words[4];
+            break;
+        case "toggle":
+            action = words[0];
+            start = words[1];
+            end = words[3];
+            break;
+    }
+
+    int startX = Int32.Parse(start.Split(',')[0]);
+    int startY = Int32.Parse(start.Split(',')[1]);
+    int endX = Int32.Parse(end.Split(',')[0]);
+    int endY = Int32.Parse(end.Split(',')[1]);
+
+    // Iterate through the x numbers.
+    for(int x = startX; x <= endX; x++){
+        // Iterate through the y values for this row.
+        for(int y = startY; y <= endY; y++){
+            switch(action){
+                case "on":
+                    lights[x,y] = true;
+                    brightness[x,y]++;
+                    break;
+                case "off":
+                    lights[x,y] = false;
+                    if(brightness[x,y] > 0){
+                        brightness[x,y]--;
+                    }
+                    break;
+                case "toggle":
+                    brightness[x,y] += 2;
+                    switch(lights[x,y]){
+                        case true:
+                            lights[x,y] = false;
+                            break;
+                        case false:
+                            lights[x,y] = true;
+                            break;
+                    }
+                    break;
+                }
+        }
+    }
+}
+
+// Count up how many lights are on.
+int lightsOn = 0;
+foreach(bool light in lights){
+    if(light == true){
+        lightsOn++;
+    }
+}
+
+// Count up the total brightness.
+int totalBrightness = 0;
+foreach(int level in brightness){
+    totalBrightness += level;
+}
+
+// Print totals.
+Console.WriteLine("Part 1: " + lightsOn);
+Console.WriteLine("Part 2: " + totalBrightness);