Make the spots clickable and have them increment their inner value.

lib/main.dart

@@ -57,7 +57,7 @@ class GameBoard extends StatelessWidget {
                 Column(children: [BoardSpot(text: "5,1")]),
               ],
             ),
-            BoardSpot(text: text),
+            BoardSpot(text: text, w: 75, h: 200),
           ],
         ),
         // Player 2 Goal
@@ -69,19 +69,35 @@ class GameBoard extends StatelessWidget {
   }
 }
 
-class BoardSpot extends StatelessWidget {
+class BoardSpot extends StatefulWidget {
   final String text;
   final double w;
   final double h;
 
   BoardSpot({super.key, required this.text, this.w = 50, this.h = 50});
 
+  @override
+  State<BoardSpot> createState() => _BoardSpotState();
+}
+
+class _BoardSpotState extends State<BoardSpot> {
+  var _marbles = 4;
   @override
   Widget build(BuildContext context) {
-    return SizedBox(
-      width: w,
-      height: h,
-      child: Center(child: Text(text, textAlign: TextAlign.center)),
+    return GestureDetector(
+      // 2. Handle the tap
+      onTap: () {
+        // 3. Update the state
+        setState(() {
+          _marbles++;
+        });
+      },
+      // 4. The sized box containing the text
+      child: SizedBox(
+        width: widget.w,
+        height: widget.h,
+        child: Center(child: Text("$_marbles", textAlign: TextAlign.center)),
+      ),
     );
   }
 }