diff --git a/www/js/game.js b/www/js/game.js
index f55c6a3..5918aae 100644
--- a/www/js/game.js
+++ b/www/js/game.js
@@ -408,17 +408,13 @@ GAME.Game = class {
         this.update_board();
     }
 
-    movement_tiles(piece, tile) {
+    movement_tiles(piece, tile, check_drop=false) {
         let tiles = [ ];
         let moves = piece.moves();
         let hex = this.board.tiles[tile].hex;
 
         let directions = moves.direction;
-        let permitted_moves =  directions;
-        let block_directions = piece.blocking;
-        if(block_directions != 0) {
-            block_directions |= BITWISE.rotate_blocks(piece.blocking);
-        }
+        let block_directions = piece.blocking | BITWISE.rotate_blocks(piece.blocking);
 
         // Check directions of movement.
         for(let mask = BITWISE.lsb(directions); directions > 0; mask = BITWISE.lsb(directions)) {
@@ -430,7 +426,7 @@ GAME.Game = class {
             if((dir_mask & 0xFFF) == 0) { dir_mask >>= 12; }
 
             // Get initial status in direction.
-            let valid = true; //(permitted_moves & mask) != 0;
+            let valid = true;
             let pieces_blocking = 0;
 
             let move_hex = hex.copy();
@@ -543,6 +539,73 @@ GAME.Game = class {
             directions &= ~mask;
         }
 
+        // Handle drop rules for promoted castle
+        if(!check_drop && piece.piece == GAME.Const.PieceId.Castle && piece.promoted) {
+            let move_hex = hex.copy();
+            let mask_back = 1 << 3;
+            if(piece.player == GAME.Const.Player.Dusk) {
+                mask_back = BITWISE.rotate_blocks(mask_back);
+            }
+            let mask_column = mask_back | BITWISE.rotate_blocks(mask_back);
+
+            let direction = GAME.Const.get_direction(BITWISE.ffs(mask_back));
+            move_hex.add(direction);
+
+            let status = (block_directions == 0 || (mask_back & block_directions) != 0);
+            
+            // Check if backward tile meets placement rules.
+            for(let i = 0; i < 9; ++i) {
+                move_hex.add(direction);
+                
+                if(HEX.is_valid_board(move_hex)) {
+                    let valid = status;
+
+                    let tile_id = HEX.hex_to_tile(move_hex);
+                    let tile_data = this.board.tiles[tile_id];
+                    let target_id = tile_data.piece;
+
+                    // Check tile is empty.
+                    if(target_id !== null) {
+                        valid = false;
+
+                        // Prevent change in blocking status
+                        if((mask_column & block_directions) != 0) {
+                            status = false;
+                        }
+                    }
+
+                    // Prevent placement that does not uncheck King.
+                    let check_direct = (this.state.check & GAME.Const.Check.Direct) != 0;
+                    let check_count = this.state.check & 0x3F;
+                    if(piece.player == (this.turn & 1) && this.state.check != 0) {
+                        if(check_direct == 0 && check_count == 1) {
+                            valid = valid && tile.checking != 0;
+                        } else {
+                            valid = false;
+                        }
+                    }
+                    
+                    // Check off-sides.
+                    if(piece.player == 0) {
+                        valid = valid && (move_hex.y <= this.board.columns[move_hex.x].extent[+(!piece.player)]);
+                    } else {
+                        valid = valid && (move_hex.y >= this.board.columns[move_hex.x].extent[+(!piece.player)]);
+                    }
+
+                    // Check if position puts king in check.
+                    let movements = this.movement_tiles(piece, tile_id, true);
+                    for(let movement of movements) {
+                        if(movement.check) {
+                            valid = false;
+                            break;
+                        }
+                    }
+
+                    tiles.push(new GAME.MovementTile(tile_id, valid, false, 0, 0));
+                } else { break; }
+            }
+        }
+
         return tiles;
     }
 
@@ -602,7 +665,7 @@ GAME.Game = class {
 
                 // Check if position puts king in check.
                 let checking = false;
-                let movements = this.movement_tiles(piece, i);
+                let movements = this.movement_tiles(piece, i, true);
                 for(let movement of movements) {
                     if(movement.check) {
                         checking = true;
@@ -717,19 +780,17 @@ GAME.Const = {
                 .add(14)
                 .add(16)
                 .add(17),
-            /*new GAME.PieceMovement()
-                .add(12)
+            new GAME.PieceMovement()
+                .add(0)
+                .add(3)
+                .add(6)
+                .add(8)
+                .add(9)
+                .add(11)
                 .add(13)
                 .add(14)
-                .add(15)
                 .add(16)
-                .add(17)
-                .add(18)
-                .add(19)
-                .add(20)
-                .add(21)
-                .add(22)
-                .add(23),*/
+                .add(17),
         ),
         new GAME.GamePiece(
             "Tower",
@@ -769,8 +830,8 @@ GAME.Const = {
                 .add(3)
                 .add(4)
                 .add(5)
-                .add_stride(7)
-                .add_stride(10),
+                .add(7)
+                .add(10),
         ),
         new GAME.GamePiece(
             "Dragon",