diff --git a/pigeon_magnet_solver/board.py b/pigeon_magnet_solver/board.py
index bc63fc4..e3c084a 100644
--- a/pigeon_magnet_solver/board.py
+++ b/pigeon_magnet_solver/board.py
@@ -1,5 +1,7 @@
 from dataclasses import dataclass
 
+from .helpers import rotate_r
+
 
 @dataclass(kw_only=True, slots=True)
 class Board:
@@ -25,6 +27,9 @@ class Board:
         else:
             return len(self.rows[0])
 
+    def __len__(self) -> int:
+        return self.height * self.width
+
     def __post_init__(self) -> None:
         # check char set
         chars = {c for c in "".join(self.rows)}
@@ -37,9 +42,8 @@ class Board:
         ), "Inconsistent width!"
 
         # check buttons
-        length = self.height * self.width
         assert all(
-            button in range(length)
+            button in range(len(self))
             for button in self.buttons
         ), "Invalid buttons!"
 
@@ -72,16 +76,36 @@ class Board:
             for column in self.columns
         )
 
-    def __idx_to_xy(self, index: int) -> tuple[int, int]:
-        return index % self.width, index // self.width
+    def __getitem__(self, key: tuple[int, int]) -> str:
+        row, col = key
 
-    def is_clickable(self, index: int) -> bool:
-        # check index
-        assert index in self.buttons, f"{index} is not a button!"
+        if row not in range(self.height) or col not in range(self.width):
+            return "x"
 
-        # check is button
-        x, y = self.__idx_to_xy(index)
-        return self.rows[y][x] == "1"
+        return self.rows[row][col]
+
+    def __setitem__(self, key: tuple[int, int], value: str):
+        row, col = key
+
+        if row not in range(self.height) or col not in range(self.width):
+            return
+
+        old_row = self.rows[row]
+        self.rows[row] = old_row[:col] + value + old_row[col+1:]
 
     def click(self, index: int) -> None:
-        assert self.is_clickable(index), f"{index} is not clickable!"
+        # check is clickable
+        row, col = index // self.width, index % self.width
+        assert self.rows[row][col] == "1", f"{index} is not clickable!"
+
+        nb_rc = [
+            (row - 1, col),
+            (row, col + 1),
+            (row + 1, col),
+            (row, col - 1),
+        ]
+
+        nb_str = "".join(self[*rc] for rc in nb_rc)
+
+        for rc, val in zip(nb_rc, rotate_r(nb_str)):
+            self[rc] = val
diff --git a/pigeon_magnet_solver/main.py b/pigeon_magnet_solver/main.py
index cf20f81..3f8982e 100755
--- a/pigeon_magnet_solver/main.py
+++ b/pigeon_magnet_solver/main.py
@@ -5,7 +5,18 @@ from .board import Board
 
 def main() -> None:
     board = Board.default_puzzle
+    print(board)
+    print()
 
+    board.click(2)  # not a button!
+    print(board)
+    print()
+
+    board.click(4)
+    print(board)
+    print()
+
+    board.click(5)
     print(board)
 
 
diff --git a/tests/test_board.py b/tests/test_board.py
index 18d52e7..dcdb9ad 100644
--- a/tests/test_board.py
+++ b/tests/test_board.py
@@ -1,3 +1,5 @@
+import pytest
+
 from pigeon_magnet_solver.board import Board
 
 
@@ -11,7 +13,6 @@ def test_default():
     assert board.binary_repr == (4, 11, 3), "Wrong binary repr"
     assert board.solution_class == (1, 3, 2), "Wrong solution class"
 
-    assert board.is_clickable(3) is False, "Button 3 should be inactive"
-    assert board.is_clickable(4) is True, "Button 4 should be active"
-    assert board.is_clickable(5) is True, "Button 5 should be active"
-    assert board.is_clickable(7) is False, "Button 7 should be inactive"
+    for idx in (3, 7):
+        with pytest.raises(AssertionError):
+            board.click(idx)