diff --git a/src/app.rs b/src/app.rs
index 91b8f94..db6e6f2 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -27,6 +27,8 @@ impl Game for App {
     }
 
     fn load(&mut self, _asset_store: &mut AssetStore) {
+        self.board.generate_tile();
+        self.board.generate_tile();
     }
 
     fn key_press(
@@ -35,10 +37,10 @@ impl Game for App {
         _asset_store: &mut AssetStore
     ) {
         if key == keyboard::Left {
-            self.board.test_tile.start_moving(settings::TILE_MOVE_TIME, 0, 0);
+            self.board.merge_from_right_to_left();
         }
         if key == keyboard::Right {
-            self.board.test_tile.start_moving(settings::TILE_MOVE_TIME, 3, 0);
+            self.board.merge_from_left_to_right();
         }
     }
 
diff --git a/src/board.rs b/src/board.rs
index a881deb..eca8bf9 100644
--- a/src/board.rs
+++ b/src/board.rs
@@ -1,37 +1,177 @@
 
+use std::iter::range_step;
+use rand::random;
 use graphics::*;
 use piston::*;
 use settings;
-use tile::Tile;
+use tile::{
+    Tile,
+    TileStatic,
+};
 
 pub struct Board {
-    center: [f64, ..2],
-    tiles: [[Option<Tile>, ..settings::TILE_WIDTH], ..settings::TILE_HEIGHT],
-    pub test_tile: Tile,
+    tiles: Vec<Tile>,
 }
 
 impl Board {
     pub fn new() -> Board {
         Board {
-            center: [0.0, 0.0],
-            tiles: [
-                [None, None, None, None],
-                [None, None, None, None],
-                [None, None, None, None],
-                [None, None, None, None],
-            ],
-            test_tile: Tile::new(16, 0, 0),
+            tiles: Vec::<Tile>::new(),
+        }
+    }
+
+    pub fn generate_tile(&mut self) {
+        if self.tiles.len() == (settings::TILE_WIDTH * settings::TILE_HEIGHT) as uint {
+            return;
+        }
+
+        'generating: loop {
+            let x = (random::<uint>() % settings::TILE_WIDTH as uint) as int;
+            let y = (random::<uint>() % settings::TILE_HEIGHT as uint) as int;
+            if self.get_tile(x, y).is_none() {
+                self.tiles.push(Tile::new(2, x, y));
+                break;
+            }
         }
     }
 
     pub fn update(&mut self, dt: f64) {
-        self.test_tile.update(dt);
+        for tile in self.tiles.mut_iter() {
+            tile.update(dt);
+        }
     }
 
     pub fn render(&self, c: &Context, gl: &mut Gl) {
         self.render_board(c, gl);
         self.render_tiles(c, gl);
-        self.test_tile.render(c, gl);
+    }
+
+    pub fn can_merge(&self) -> bool {
+        for row in range(0, settings::TILE_HEIGHT) {
+            if !self.can_merge_row(row) {
+                return false;
+            }
+        }
+        true
+    }
+
+    pub fn merge_from_left_to_right(&mut self) {
+        self.merge_row(settings::TILE_WIDTH - 1, -1, -1);
+    }
+
+    pub fn merge_from_right_to_left(&mut self) {
+        self.merge_row(0, settings::TILE_WIDTH, 1);
+    }
+
+    fn merge_row(&mut self, x_start: int, x_end: int, x_step: int) {
+        if self.is_locking() {
+            return;
+        }
+
+        // move all tiles to right place
+        for row in range(0, settings::TILE_HEIGHT) {
+            for col in range_step(x_start, x_end, x_step) {
+                match self.get_mut_tile(col, row) {
+                    None => {
+                        match self.get_mut_next_tile(col, row, x_step, 0) {
+                            Some(ref mut tile) => {
+                                tile.start_moving(col, row);
+                            },
+                            _ => {},
+                        }
+                    },
+                    _ => {},
+                }
+            }
+        }
+
+        // merge
+
+        self.generate_tile();
+    }
+
+    fn can_merge_row(&self, row: int) -> bool {
+        for col in range(0, settings::TILE_WIDTH) {
+            match self.get_tile(col, row) {
+                Some(ref tile) => {
+                    match self.get_next_tile(tile.tile_x, tile.tile_y, 1, 0) {
+                        Some(ref s_tile) => {
+                            if tile.score == s_tile.score {
+                                return true;
+                            }
+                        },
+                        _ => {},
+                    }
+                },
+                None => {},
+            }
+        }
+        false
+    }
+
+    fn is_locking(&self) -> bool {
+        for tile in self.tiles.iter() {
+            if tile.status != TileStatic {
+                return true;
+            }
+        }
+        false
+    }
+
+    /// Returns next tile right besides (x, y)
+    fn get_next_tile<'a>(&'a self, x: int, y: int, step_x: int, step_y: int) -> Option<&'a Tile> {
+        let mut x = x + step_x;
+        let mut y = y + step_y;
+        while x >= 0 && x < settings::TILE_WIDTH
+              && y >= 0 && y < settings::TILE_HEIGHT {
+            let tile = self.get_tile(x, y);
+            if tile.is_some() {
+                return tile;
+            }
+            x += step_x;
+            y += step_y;
+        }
+        None
+    }
+
+    fn get_mut_next_tile<'a>(&'a mut self, x: int, y: int, step_x: int, step_y: int) -> Option<&'a mut Tile> {
+        let mut x = x + step_x;
+        let mut y = y + step_y;
+        let mut found = false;
+        while x >= 0 && x < settings::TILE_WIDTH
+              && y >= 0 && y < settings::TILE_HEIGHT {
+            let tile = self.get_tile(x, y);
+            if tile.is_some() {
+                found = true;
+                break;
+            }
+            x += step_x;
+            y += step_y;
+        }
+
+        if found {
+            self.get_mut_tile(x, y)
+        } else {
+            None
+        }
+    }
+
+    fn get_tile<'a>(&'a self, x: int, y: int) -> Option<&'a Tile> {
+        for tile in self.tiles.iter() {
+            if tile.tile_x == x && tile.tile_y == y {
+                return Some(tile);
+            }
+        }
+        None
+    }
+
+    fn get_mut_tile<'a>(&'a mut self, x: int, y: int) -> Option<&'a mut Tile> {
+        for tile in self.tiles.mut_iter() {
+            if tile.tile_x == x && tile.tile_y == y {
+                return Some(tile);
+            }
+        }
+        None
     }
 
     fn render_board(&self, c: &Context, gl: &mut Gl) {
@@ -70,7 +210,7 @@ impl Board {
     fn render_tiles(&self, c: &Context, gl: &mut Gl) {
         for row in range(0, settings::TILE_HEIGHT) {
             for col in range(0, settings::TILE_WIDTH) {
-                match self.tiles[row][col] {
+                match self.get_tile(col, row) {
                     Some(ref tile) => {
                         tile.render(c, gl);
                     },
diff --git a/src/main.rs b/src/main.rs
index 25cba57..8ee46ca 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,7 @@
 
 #![feature(globs)]
 
+extern crate collections;
 extern crate rand;
 
 extern crate graphics;
diff --git a/src/settings.rs b/src/settings.rs
index 355b7e6..24336cd 100644
--- a/src/settings.rs
+++ b/src/settings.rs
@@ -14,8 +14,8 @@ pub static BOARD_SIZE: [f64, ..2] = [
 ];
 pub static BOARD_OFFSET_Y: f64 = 128.0;
 
-pub static TILE_WIDTH: uint = 4;
-pub static TILE_HEIGHT: uint = 4;
+pub static TILE_WIDTH: int = 4;
+pub static TILE_HEIGHT: int = 4;
 pub static TILE_SIZE: f64 = 96.0;
 pub static TILE_PADDING: f64 = 16.0;
 pub static TILE_BACKGROUND_COLOR: [f32, ..4] = [187.0 / 255.0, 173.0 / 255.0, 160.0 / 255.0, 1.0];
diff --git a/src/tile.rs b/src/tile.rs
index 45c3915..4def4c5 100644
--- a/src/tile.rs
+++ b/src/tile.rs
@@ -3,17 +3,18 @@ use graphics::*;
 use piston::*;
 use settings;
 
-enum TileState {
+#[deriving(Eq)]
+pub enum TileState {
     TileStatic,
-    /// (t, x, y, destination_tile_x, destination_tile_y)
-    TileMoving(f64, f64, f64, int, int),
+    /// (t, x, y)
+    TileMoving(f64, f64, f64),
 }
 
 pub struct Tile {
-    score: int,
-    tile_x: int,
-    tile_y: int,
-    status: TileState,
+    pub score: int,
+    pub tile_x: int,
+    pub tile_y: int,
+    pub status: TileState,
 }
 
 impl Tile {
@@ -32,27 +33,22 @@ impl Tile {
         (x, y)
     }
 
-    pub fn start_moving(&mut self, t: f64, destination_tile_x: int, destination_tile_y: int) {
-        match self.status {
-            TileStatic => {
-                let (x, y) = Tile::tile_to_pos(self.tile_x, self.tile_y);
-                self.status = TileMoving(t, x, y, destination_tile_x, destination_tile_y);
-            },
-            _ => {},
-        }
+    pub fn start_moving(&mut self, destination_tile_x: int, destination_tile_y: int) {
+        let (x, y) = Tile::tile_to_pos(self.tile_x, self.tile_y);
+        self.status = TileMoving(settings::TILE_MOVE_TIME, x, y);
+        self.tile_x = destination_tile_x;
+        self.tile_y = destination_tile_y;
     }
 
     pub fn update(&mut self, dt: f64) {
         match self.status {
-            TileMoving(t, x, y, dtx, dty) => {
+            TileMoving(t, x, y) => {
                 if dt >= t {
-                    self.tile_x = dtx;
-                    self.tile_y = dty;
                     self.status = TileStatic;
                 } else {
-                    let (dx, dy) = Tile::tile_to_pos(dtx, dty);
+                    let (dx, dy) = Tile::tile_to_pos(self.tile_x, self.tile_y);
                     let factor = dt / t;
-                    self.status = TileMoving(t - dt, x + factor * (dx - x), y + factor * (dy - y), dtx, dty);
+                    self.status = TileMoving(t - dt, x + factor * (dx - x), y + factor * (dy - y));
                 }
             },
             TileStatic => {},
@@ -62,12 +58,12 @@ impl Tile {
     pub fn render(&self, c: &Context, gl: &mut Gl) {
         let mut pos = (0.0, 0.0);
         match self.status {
+            TileMoving(_, x, y) => {
+                pos = (x, y);
+            },
             TileStatic => {
                 pos = Tile::tile_to_pos(self.tile_x, self.tile_y);
             },
-            TileMoving(_, x, y, _, _) => {
-                pos = (x, y);
-            }
         }
         let (x, y) = pos;
         let color = self.get_color();