diff --git a/source/GridMap.gd b/source/GridMap.gd
index cc13dc8..c77e4d0 100644
--- a/source/GridMap.gd
+++ b/source/GridMap.gd
@@ -6,16 +6,17 @@ const ExplodingLine = preload("res://ExplodingLine.tscn")
 const EMPTY_CELL = -1
 const MINO = 0
 
-export (int) var NB_LINES = 20
-export (int) var NB_COLLUMNS = 10
-
 var exploding_lines = []
+var nb_collumns
+var nb_lines
 
 func _ready():
-	for y in range(NB_LINES):
+	nb_collumns = int($Matrix.scale.x)
+	nb_lines = int($Matrix.scale.y)
+	for y in range(nb_lines):
 		exploding_lines.append(ExplodingLine.instance())
 		add_child(exploding_lines[y])
-		exploding_lines[y].translation = Vector3(NB_COLLUMNS/2, y, 1)
+		exploding_lines[y].translation = Vector3(nb_collumns/2, y, 1)
 
 func clear():
 	for position in get_used_cells():
@@ -23,7 +24,7 @@ func clear():
 
 func is_free_cell(position):
 	return (
-		0 <= position.x and position.x < NB_COLLUMNS
+		0 <= position.x and position.x < nb_collumns
 		and position.y >= 0
 		and get_cell_item(position.x, position.y, 0) == GridMap.INVALID_CELL_ITEM
 	)
@@ -43,7 +44,7 @@ func possible_positions(initial_positions, movement):
 func lock(piece):
 	var minoes_over_grid = 0
 	for position in piece.positions():
-		if position.y >= NB_LINES:
+		if position.y >= nb_lines:
 			minoes_over_grid += 1
 		set_cell_item(position.x, position.y, 0, MINO)
 	return minoes_over_grid < Tetromino.NB_MINOES
@@ -51,15 +52,15 @@ func lock(piece):
 func clear_lines():
 	var line_cleared
 	var lines_cleared = 0
-	for y in range(NB_LINES-1, -1, -1):
+	for y in range(nb_lines-1, -1, -1):
 		line_cleared = true
-		for x in range(NB_COLLUMNS):
+		for x in range(nb_collumns):
 			if not get_cell_item(x, y, 0) == MINO:
 				line_cleared = false
 				break
 		if line_cleared:
-			for y2 in range(y, NB_LINES+2):
-				for x in range(NB_COLLUMNS):
+			for y2 in range(y, nb_lines+2):
+				for x in range(nb_collumns):
 					set_cell_item(x, y2, 0, get_cell_item(x, y2+1, 0))
 			lines_cleared += 1
 			exploding_lines[y].emitting = true
diff --git a/source/Main.gd b/source/Main.gd
index 1bd54d4..597929c 100644
--- a/source/Main.gd
+++ b/source/Main.gd
@@ -11,9 +11,6 @@ const TetroZ = preload("res://Tetrominos/TetroZ.tscn")
 
 const password = "TETRIS 3000"
 
-const NEXT_POSITION = Vector3(13, 16, 0)
-const START_POSITION = Vector3(5, 20, 0)
-const HOLD_POSITION = Vector3(-5, 16, 0)
 const THERE = Vector3(0, 0, 0)
 
 const movements = {
@@ -67,10 +64,10 @@ func new_piece():
 	if current_piece:
 		remove_child(current_piece)
 	current_piece = next_piece
-	current_piece.translation = START_POSITION
+	current_piece.translation = $GridMap/Matrix/Position3D.translation
 	current_piece.emit_trail(true)
 	next_piece = random_piece()
-	next_piece.translation = NEXT_POSITION
+	next_piece.translation = $GridMap/Next/Position3D.translation
 	if move(THERE):
 		$DropTimer.start()
 		$LockDelay.start()
@@ -191,9 +188,9 @@ func hold():
 		current_piece = held_piece
 		held_piece = swap
 		held_piece.emit_trail(false)
-		held_piece.translation = HOLD_POSITION
+		held_piece.translation = $GridMap/Hold/Position3D.translation
 		if current_piece:
-			current_piece.translation = START_POSITION
+			current_piece.translation = $GridMap/Matrix/Position3D.translation
 			current_piece.emit_trail(true)
 		else:
 			new_piece()
@@ -208,7 +205,6 @@ func resume():
 	$controls_ui.visible = false
 	$Stats.visible = true
 	$GridMap.visible = true
-	$Backs.visible = true
 	current_piece.visible = true
 	if held_piece:
 		held_piece.visible = true
@@ -220,7 +216,6 @@ func pause(hide=true):
 	if hide:
 		$Stats.visible = false
 		$GridMap.visible = false
-		$Backs.visible = false
 		current_piece.visible = false
 		if held_piece:
 			held_piece.visible = false
diff --git a/source/Main.tscn b/source/Main.tscn
index bdbe41b..30a9f24 100644
--- a/source/Main.tscn
+++ b/source/Main.tscn
@@ -313,6 +313,7 @@ _sections_unfolded = [ "Light", "Transform" ]
 
 [node name="GridMap" type="GridMap" parent="." index="3"]
 
+visible = false
 theme = ExtResource( 3 )
 cell_size = Vector3( 1, 1, 1 )
 cell_octant_size = 8
@@ -331,16 +332,10 @@ __meta__ = {
 "_editor_clip_": 1,
 "_editor_floor_": Vector3( 0, -1, 0 )
 }
-NB_LINES = 20
-NB_COLLUMNS = 10
 
-[node name="Backs" type="Spatial" parent="." index="4"]
+[node name="Matrix" type="MeshInstance" parent="GridMap" index="0"]
 
-visible = false
-
-[node name="GridBack" type="MeshInstance" parent="Backs" index="0"]
-
-transform = Transform( 10, 0, 0, 0, 20, 0, 0, 0, 1, 4.5, 9.5, 0 )
+transform = Transform( 8.5, 0, 0, 0, 20, 0, 0, 0, 1, 4.5, 9.5, 0 )
 layers = 1
 material_override = null
 cast_shadow = 1
@@ -355,7 +350,12 @@ skeleton = NodePath("..")
 material/0 = null
 _sections_unfolded = [ "Transform" ]
 
-[node name="HoldBack" type="MeshInstance" parent="Backs" index="1"]
+[node name="Position3D" type="Position3D" parent="GridMap/Matrix" index="0"]
+
+transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 5, 20, 0 )
+_sections_unfolded = [ "Transform" ]
+
+[node name="Hold" type="MeshInstance" parent="GridMap" index="1"]
 
 transform = Transform( 7, 0, 0, 0, 7, 0, 0, 0, 1, -5, 16, 0 )
 layers = 1
@@ -372,7 +372,12 @@ skeleton = NodePath("..")
 material/0 = null
 _sections_unfolded = [ "Transform" ]
 
-[node name="NextBack" type="MeshInstance" parent="Backs" index="2"]
+[node name="Position3D" type="Position3D" parent="GridMap/Hold" index="0"]
+
+transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, -5, 16, 0 )
+_sections_unfolded = [ "Transform" ]
+
+[node name="Next" type="MeshInstance" parent="GridMap" index="2"]
 
 transform = Transform( 7, 0, 0, 0, 7, 0, 0, 0, 1, 14, 16, 0 )
 layers = 1
@@ -389,41 +394,47 @@ skeleton = NodePath("..")
 material/0 = null
 _sections_unfolded = [ "Transform" ]
 
-[node name="DropTimer" type="Timer" parent="." index="5"]
+[node name="Position3D" type="Position3D" parent="GridMap/Next" index="0"]
+
+transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 13, 16, 0 )
+_sections_unfolded = [ "Transform" ]
+
+[node name="DropTimer" type="Timer" parent="." index="4"]
 
 process_mode = 1
 wait_time = 1.0
 one_shot = false
 autostart = false
 
-[node name="LockDelay" type="Timer" parent="." index="6"]
+[node name="LockDelay" type="Timer" parent="." index="5"]
 
 process_mode = 1
 wait_time = 0.5
 one_shot = true
 autostart = false
 
-[node name="AutoShiftDelay" type="Timer" parent="." index="7"]
+[node name="AutoShiftDelay" type="Timer" parent="." index="6"]
 
 process_mode = 1
 wait_time = 0.2
 one_shot = true
 autostart = false
 
-[node name="AutoShiftTimer" type="Timer" parent="." index="8"]
+[node name="AutoShiftTimer" type="Timer" parent="." index="7"]
 
 process_mode = 1
 wait_time = 0.04
 one_shot = false
 autostart = false
 
-[node name="MidiPlayer" parent="." index="9" instance=ExtResource( 5 )]
+[node name="MidiPlayer" parent="." index="8" instance=ExtResource( 5 )]
 
 editor/display_folded = true
 script = ExtResource( 6 )
 file = "res://midi/Tetris - Song A.mid"
 volume_db = -24
 loop = true
+loop_start = 1.81
 soundfont = "res://midi/TimGM6mb.sf2"
 
 [node name="LineCLearTimer" type="Timer" parent="MidiPlayer" index="1"]
@@ -433,7 +444,7 @@ wait_time = 1.41
 one_shot = true
 autostart = false
 
-[node name="FlashText" type="Control" parent="." index="10"]
+[node name="FlashText" type="Control" parent="." index="9"]
 
 anchor_left = 0.5
 anchor_top = 0.5
@@ -487,7 +498,7 @@ anims/Flash = SubResource( 7 )
 blend_times = [  ]
 _sections_unfolded = [ "Playback Options" ]
 
-[node name="Stats" parent="." index="11" instance=ExtResource( 9 )]
+[node name="Stats" parent="." index="10" instance=ExtResource( 9 )]
 
 visible = false
 anchor_left = 0.0
@@ -499,13 +510,13 @@ margin_top = -260.0
 margin_right = 130.0
 margin_bottom = -50.0
 
-[node name="controls_ui" parent="." index="12" instance=ExtResource( 10 )]
+[node name="controls_ui" parent="." index="11" instance=ExtResource( 10 )]
 
 visible = false
 
-[node name="Start" parent="." index="13" instance=ExtResource( 11 )]
+[node name="Start" parent="." index="12" instance=ExtResource( 11 )]
 
-[node name="ReplayButton" type="Button" parent="." index="14"]
+[node name="ReplayButton" type="Button" parent="." index="13"]
 
 visible = false
 anchor_left = 1.0