diff --git a/src/board.rs b/src/board.rs
index 4a0706c..5c8e1d1 100644
--- a/src/board.rs
+++ b/src/board.rs
@@ -21,6 +21,32 @@ impl Board {
         }
     }
 
+    pub fn moveable(&self, direction: Direction) -> bool {
+        let player_next_position = self.level.player_position + direction.to_vector();
+        if self
+            .level
+            .get_unchecked(&player_next_position)
+            .intersects(Tile::Wall)
+        {
+            return false;
+        }
+        if self
+            .level
+            .get_unchecked(&player_next_position)
+            .intersects(Tile::Crate)
+        {
+            let crate_next_position = player_next_position + direction.to_vector();
+            if self
+                .level
+                .get_unchecked(&crate_next_position)
+                .intersects(Tile::Crate | Tile::Wall)
+            {
+                return false;
+            }
+        }
+        return true;
+    }
+
     pub fn move_or_push(&mut self, direction: Direction) {
         let direction_vector = direction.to_vector();
         let player_next_position = self.level.player_position + direction_vector;
diff --git a/src/solver/solver.rs b/src/solver/solver.rs
index 2cb5994..adb57e7 100644
--- a/src/solver/solver.rs
+++ b/src/solver/solver.rs
@@ -120,6 +120,10 @@ impl Solver {
     }
 
     fn minimum_push_count_to_nearest_target(&self, position: &Vector2<i32>) -> Option<usize> {
+        // TODO: 优化求解器最小推动数计算方法
+        // 从目标开始逆推, 得到全部可达位置的下界.
+        // 若以存在下界, 取最小值. 若已经为更小的值, 停止搜索.
+
         if self.level.target_positions.contains(position) {
             return Some(0);
         }
@@ -207,17 +211,17 @@ impl Solver {
                 ]
                 .chunks(2)
                 {
-                    let neighbor = [
+                    let neighbors = [
                         position + directions[0].to_vector(),
                         position + directions[1].to_vector(),
                     ];
                     if !(self
                         .level
-                        .get_unchecked(&neighbor[0])
+                        .get_unchecked(&neighbors[0])
                         .intersects(Tile::Wall)
                         && self
                             .level
-                            .get_unchecked(&neighbor[1])
+                            .get_unchecked(&neighbors[1])
                             .intersects(Tile::Wall))
                     {
                         continue;
diff --git a/src/solver/state.rs b/src/solver/state.rs
index 985addc..4672424 100644
--- a/src/solver/state.rs
+++ b/src/solver/state.rs
@@ -101,6 +101,7 @@ impl State {
                     continue;
                 }
 
+                // TODO: 检测是否会产生新的死锁
                 if self.can_block_crate(&new_crate_position, solver) {
                     continue;
                 }
diff --git a/src/systems/auto_solve.rs b/src/systems/auto_solve.rs
index f0e8103..eb3c300 100644
--- a/src/systems/auto_solve.rs
+++ b/src/systems/auto_solve.rs
@@ -120,7 +120,7 @@ pub fn update_solver(
             info!("    Solution: {}", solution.lurd());
 
             for movement in &*solution {
-                player_move_or_push(movement.direction, &mut player_movement);
+                player_move(movement.direction, &mut player_movement);
             }
             next_state.set(AppState::Main);
             return;
diff --git a/src/systems/input.rs b/src/systems/input.rs
index 67316e3..a3f17bf 100644
--- a/src/systems/input.rs
+++ b/src/systems/input.rs
@@ -222,8 +222,8 @@ impl Action {
 
 pub fn player_move_to(
     target: &Vector2<i32>,
-    board: &mut crate::board::Board,
     player_movement: &mut PlayerMovement,
+    board: &crate::board::Board,
 ) {
     if let Some(path) = find_path(&board.level.player_position, target, |position| {
         board
@@ -235,12 +235,23 @@ pub fn player_move_to(
             .windows(2)
             .map(|pos| Direction::from_vector(pos[1] - pos[0]).unwrap());
         for direction in directions {
-            player_move_or_push(direction, player_movement);
+            player_move(direction, player_movement);
         }
     }
 }
 
-pub fn player_move_or_push(direction: Direction, player_movement: &mut PlayerMovement) {
+pub fn player_move(direction: Direction, player_movement: &mut PlayerMovement) {
+    player_movement.directions.push_front(direction);
+}
+
+pub fn player_move_with_check(
+    direction: Direction,
+    player_movement: &mut PlayerMovement,
+    board: &crate::board::Board,
+) {
+    if !board.moveable(direction) {
+        return;
+    }
     player_movement.directions.push_front(direction);
 }
 
@@ -291,16 +302,16 @@ pub fn handle_other_action(
     let board = &mut board.single_mut().board;
 
     if action_state.just_pressed(Action::MoveUp) {
-        player_move_or_push(Direction::Up, &mut player_movement);
+        player_move_with_check(Direction::Up, &mut player_movement, board);
     }
     if action_state.just_pressed(Action::MoveDown) {
-        player_move_or_push(Direction::Down, &mut player_movement);
+        player_move_with_check(Direction::Down, &mut player_movement, board);
     }
     if action_state.just_pressed(Action::MoveLeft) {
-        player_move_or_push(Direction::Left, &mut player_movement);
+        player_move_with_check(Direction::Left, &mut player_movement, board);
     }
     if action_state.just_pressed(Action::MoveRight) {
-        player_move_or_push(Direction::Right, &mut player_movement);
+        player_move_with_check(Direction::Right, &mut player_movement, board);
     }
 
     if action_state.just_pressed(Action::Undo) {
@@ -485,7 +496,7 @@ pub fn mouse_input(
             _ => unreachable!(),
         }
 
-        player_move_to(&grid_position, board, &mut player_movement);
+        player_move_to(&grid_position, &mut player_movement, board);
     }
 }