I've done it ! For fuck sake I've done it !

Qwirkle/QwirkleClassLibrary/Games/Game.cs

@@ -401,8 +401,13 @@ namespace QwirkleClassLibrary.Games
 
 
 
-public int GetPlayerScore(Player player, ReadOnlyCollection<Cell> cellsPlayed, Board b)
+        public int GetPlayerScore(Player player, ReadOnlyCollection<Cell> cellsPlayed, Board b)
         {
+            if (cellsPlayed.Count == 0)
+            {
+                return 0;
+            }
+            
             int score = cellsPlayed.Count;
             
             int cellsX = cellsPlayed[0].GetX;
@@ -414,11 +419,15 @@ public int GetPlayerScore(Player player, ReadOnlyCollection<Cell> cellsPlayed, B
                 {
                     cellsX = -1;
                 }
+                
                 else if (cellsY != cell.GetY && cellsY != -1)
                 {
                     cellsY = -1;
                 }
-
+            }
+            
+            foreach (var cell in cellsPlayed)
+            {
                 score += CalculateAdjacentScore(cell, b, cellsPlayed, cellsX, cellsY);
             }
 
@@ -434,7 +443,7 @@ public int GetPlayerScore(Player player, ReadOnlyCollection<Cell> cellsPlayed, B
         public int CalculateAdjacentScore(Cell cell, Board b, ReadOnlyCollection<Cell> cellsPlayed, int cellsX, int cellsY)
         {
             int score = 0;
-
+        
             var surroundingCells = new[]
             {
                 b.GetCell(cell.GetX + 1, cell.GetY),
@@ -442,20 +451,20 @@ public int GetPlayerScore(Player player, ReadOnlyCollection<Cell> cellsPlayed, B
                 b.GetCell(cell.GetX, cell.GetY + 1),
                 b.GetCell(cell.GetX, cell.GetY - 1)
             };
-
+        
             foreach (var adjacentCell in surroundingCells)
             {
                 if (adjacentCell?.GetTile == null || cellsPlayed.Contains(adjacentCell))
                 {
                     continue;
                 }
-
+        
                 int dx = adjacentCell.GetX - cell.GetX;
                 int dy = adjacentCell.GetY - cell.GetY;
                 
                 score += CalculateLineScore(cell, dx, dy, b, cellsX, cellsY);
             }
-
+        
             return score;
         }