diff --git a/store/src/board.rs b/store/src/board.rs
index 220121a..0bf6336 100644
--- a/store/src/board.rs
+++ b/store/src/board.rs
@@ -3,7 +3,7 @@ use crate::Error;
 use serde::{Deserialize, Serialize};
 use std::fmt;
 
-/// field (aka 'point') position on the board (from 1 to 24)
+/// field (aka 'point') position on the board (from 0 to 24, 0 being 'outside')
 pub type Field = usize;
 
 #[derive(Debug, Copy, Clone, Serialize, PartialEq, Deserialize)]
@@ -14,12 +14,22 @@ pub struct CheckerMove {
 
 impl CheckerMove {
     pub fn new(from: Field, to: Field) -> Result<Self, Error> {
-        if from < 1 || 24 < from || to < 1 || 24 < to {
+        // check if the field is on the board
+        // we allow 0 for 'to', which represents the exit of a checker
+        if from < 1 || 24 < from || 24 < to{
             return Err(Error::FieldInvalid);
         }
+        // check that the destination is after the origin field
+        if to < from && to != 0 {
+            return Err(Error::MoveInvalid);
+        }
         Ok(CheckerMove { from, to })
     }
 
+    pub fn get_from(&self) -> Field {
+        self.from
+    }
+
     pub fn get_to(&self) -> Field {
         self.to
     }
@@ -106,6 +116,11 @@ impl Board {
             return Err(Error::FieldInvalid);
         }
 
+        // the exit : no checker added to the board
+        if field == 0 {
+            return Ok(())
+        }
+
         if self.blocked(color, field)? {
             return Err(Error::FieldBlocked);
         }
@@ -134,10 +149,15 @@ impl Board {
 
     /// Check if a field is blocked for a player
     pub fn blocked(&self, color: &Color, field: Field) -> Result<bool, Error> {
-        if field < 1 || 24 < field {
+        if 24 < field {
             return Err(Error::FieldInvalid);
         }
 
+        // the exit is never 'blocked'
+        if field == 0 {
+            return Ok(false)
+        }
+
         // the square is blocked on the opponent rest corner or if there are opponent's men on the square
         match color {
             Color::White => {
@@ -157,11 +177,11 @@ impl Board {
         }
     }
 
-    pub fn get_checkers_color(&self, field: Field) -> Result<Option<&Color>, Error> {
+    pub fn get_field_checkers(&self, field: Field) -> Result<(u8, Option<&Color>), Error> {
         if field < 1 || field > 24 {
             return Err(Error::FieldInvalid);
         }
-        let checkers_count = self.positions[field - 1]; 
+        let checkers_count = self.positions[field - 1];
         let color = if checkers_count < 0 {
             Some(&Color::Black)
         } else if checkers_count > 0 {
@@ -169,7 +189,16 @@ impl Board {
         } else {
             None
         };
-        Ok(color)
+        Ok((checkers_count.abs() as u8, color))
+    }
+
+    pub fn get_checkers_color(&self, field: Field) -> Result<Option<&Color>, Error> {
+        self.get_field_checkers(field).map(|(count, color)| color)
+    }
+
+    // Get the corner field for the color
+    pub fn get_color_corner(&self, color: &Color) -> Field {
+        if color == &Color::White { 12 } else { 13 }
     }
 
     pub fn move_possible(&self, color: &Color, cmove: CheckerMove) -> bool {
@@ -231,7 +260,7 @@ mod tests {
     #[test]
     fn blocked_outofrange() -> Result<(), Error> {
         let board = Board::new();
-        assert!(board.blocked( &Color::White, 0).is_err());
+        assert!(!board.blocked( &Color::White, 0).is_err());
         assert!(board.blocked( &Color::White, 28).is_err());
         Ok(())
     }
@@ -255,7 +284,7 @@ mod tests {
     fn set_field_blocked() {
         let mut board = Board::new();
         assert!(
-            board.set( &Color::White, 0, 24)
+            board.set( &Color::White, 24, 2)
             .is_err()
             );
     }
diff --git a/store/src/game.rs b/store/src/game.rs
index cfc5164..488caf8 100644
--- a/store/src/game.rs
+++ b/store/src/game.rs
@@ -229,13 +229,16 @@ impl GameState {
                 }
 
                 // Check move is physically possible
-                if !self.board.move_possible(&self.players[player_id].color, moves.0){
-                    return false;
-                }
-                if !self.board.move_possible(&self.players[player_id].color, moves.1){
-                    return false;
-                }
+                let color = &self.players[player_id].color;
+                if !self.board.move_possible(color, moves.0) || 
+                    !self.board.move_possible(color, moves.1) {
+                        return false;
+                    }
+
                 // Check move is allowed by the rules (to desactivate when playing with schools)
+                if !self.moves_allowed(color, moves) {
+                    return false;
+                }
             }
         }
 
@@ -243,6 +246,29 @@ impl GameState {
         true
     }
 
+    fn moves_allowed(&self, color: &Color, moves: &(CheckerMove, CheckerMove)) -> bool {
+        // ------- corner rules ----------
+        let corner_field: Field = self.board.get_color_corner(color);
+        let (corner_count, _color) = self.board.get_field_checkers(corner_field).unwrap();
+        let (from0, to0, from1, to1) = (moves.0.get_from(), moves.0.get_to(), moves.1.get_from(), moves.1.get_to());
+        // 2 checkers must go at the same time on an empty corner
+        if (to0 == corner_field || to1 == corner_field) && 
+            (to0 != to1) && corner_count == 0 {
+                return false;
+        }
+        
+        // the lat 2 checkers of a corner must leave at the same time
+        if (from0 == corner_field || from1 == corner_field) && 
+            (from0 != from1) && corner_count == 2 {
+                return false;
+        }
+        
+        // ------- exit rules ----------
+
+        // no rule was broken
+        true
+    }
+
     /// Consumes an event, modifying the GameState and adding the event to its history
     /// NOTE: consume assumes the event to have already been validated and will accept *any* event passed to it
     pub fn consume(&mut self, valid_event: &GameEvent) {