Partial rewrite, missing:

- Correctly parsing incoming messages
- Sending the gamestate after relevant actions

Mau/Card.cs

@@ -25,6 +25,31 @@ public class Card
     }
 }
 
+public static class CardExtensions
+{
+    public static bool IsSameCard(this Card card1, Card card2)
+    {
+        return card1.IsSameCardType(card2) && card1.IsSameCardValue(card2);
+    }
+    
+    public static bool IsSameCardType(this Card card1, Card card2)
+    {
+        return card1.CardType == card2.CardType;
+    }
+    
+    public static bool IsSameCardValue(this Card card1, Card card2)
+    {
+        return card1.CardValue == card2.CardValue;
+    }
+    
+    public static bool CanBePlayedOn(this Card playedCard, Card currentCard)
+    {
+        return playedCard.IsSameCardType(currentCard)
+            || playedCard.IsSameCardValue(currentCard)
+            || playedCard.CardType == CardType.JOKER;
+    }
+}
+
 public enum CardType
 {
     SPADES,