diff --git a/player/player.gd b/player/player.gd
index fe99f5a..48f08e0 100644
--- a/player/player.gd
+++ b/player/player.gd
@@ -10,37 +10,57 @@ const gear_slots = ["1", "2", "3"]
 
 var starting_gear = preload("res://gears/ball.tscn")
 
-var health = 100
 var suspended = false
 var direction = Vector3.ZERO
 var target_velocity = Vector3.ZERO
 
+var _health = 100
+
+# Player UI
+
 func resize_ui():
-	var bpui_h = 200
+	var hud_h = 200
 	var size = get_viewport().get_visible_rect().size
 	$Message.size.x = size.x
-	$BackpackUI.size.x = size.x
-	$BackpackUI.size.y = bpui_h
-	$BackpackUI.position.x = 0
-	$BackpackUI.position.y = size.y - bpui_h
+	$HUD.size.x = size.x
+	$HUD.size.y = hud_h
+	$HUD.position.x = 0
+	$HUD.position.y = size.y - hud_h
 
-func make_backpack_ui():
-	var text = "Holding " + $Pivot/Container/Gear.gear_name()
+func make_hud():
+	var text = ""
 	for node in $Backpack.get_children():
 		if not node is Gear:
 			continue
-		text += "\n%s (%s)" % [node.gear_name(), node.name]
-	$BackpackUI.text = text
+		text += "%s (%s)\n" % [node.gear_name(), node.name]
+	text += "Holding " + $Pivot/Container/Gear.gear_name() + "\n"
+	text += str(health()) + " hp"
+	$HUD.text = text
 
 func message(string):
 	$Message.text = string
 	$Message.visible = true
 	$Message/VanishTimer.start()
 
+# State functions
+
+func harm(hp):
+	assert(hp >= 0)
+	_health -= hp
+	make_hud()
+
+func heal(hp):
+	assert(hp >= 0)
+	_health += hp
+	make_hud()
+
+func health():
+	return _health
+
 func die():
 	suspended = true
 	visible = false
-	$BackpackUI.visible = false
+	$HUD.visible = false
 
 	# strip gears
 	for gear in $Backpack.get_children():
@@ -53,7 +73,7 @@ func die():
 func respawn():
 	position = Vector3(spawn)
 	$CameraGimbal.reset()
-	health = 100
+	_health = 100
 	visible = true
 	suspended = false
 
@@ -61,8 +81,8 @@ func respawn():
 	var gear = starting_gear.instantiate()
 	$Pivot/Container.add_child(gear)
 
-	make_backpack_ui()
-	$BackpackUI.visible = true
+	make_hud()
+	$HUD.visible = true
 
 # Backpack functions
 
@@ -87,7 +107,7 @@ func use_backpack_slot(n):
 		old.reparent($Backpack, false)
 		get_node(gear_node).reparent($Pivot/Container, false)
 		get_node("Pivot/Container/" + n).name = "Gear"
-		make_backpack_ui()
+		make_hud()
 		return
 	# couldn't find a free slot, so replace
 	# the new slot with the current gear
@@ -95,7 +115,7 @@ func use_backpack_slot(n):
 	old.reparent($Backpack, false)
 	old.name = n
 	get_node("Pivot/Container/" + n).name = "Gear"
-	make_backpack_ui()
+	make_hud()
 	return
 
 func equip(gear: Gear):
@@ -120,14 +140,14 @@ func equip(gear: Gear):
 		new_gear = gear.duplicate()
 		new_gear.name = "Gear"
 		$Pivot/Container.add_child(new_gear)
-		make_backpack_ui()
+		make_hud()
 		message("You picked up a " + gear_name + "!")
 		return true
 	# if no slots are free
 	message("Backpack full")
 	return false
 
-# Player movement and engine callbacks
+# Player mechanics
 
 func move_player(x, z):
 	var camera_basis = $CameraGimbal.get_global_transform().basis
@@ -148,19 +168,7 @@ func move_player(x, z):
 	if x != 0:
 		direction += camera_basis.x * x
 
-func _ready():
-	get_viewport().size_changed.connect(resize_ui)
-	resize_ui()
-	respawn()
-
-func _physics_process(delta):
-	if suspended:
-		return
-
-	if health < 1 or position.y <= -1000:
-		die()
-
-	# UI and backpack keys
+func do_backpack_keys():
 	if Input.is_action_just_pressed("backpack_1"):
 		use_backpack_slot("1")
 	if Input.is_action_just_pressed("backpack_2"):
@@ -168,7 +176,7 @@ func _physics_process(delta):
 	if Input.is_action_just_pressed("backpack_3"):
 		use_backpack_slot("3")
 
-	# Movement keys
+func do_movement(delta):
 	var mx = 0
 	var mz = 0
 
@@ -196,7 +204,7 @@ func _physics_process(delta):
 
 	move_and_slide()
 
-	# Gear uses
+func do_gears():
 	var gear = $Pivot/Container/Gear
 	assert(gear is Gear)
 	if gear.continuous():
@@ -206,6 +214,27 @@ func _physics_process(delta):
 		if Input.is_action_just_pressed("gear_use"):
 			gear.use(self)
 
+# Engine callbacks
+
+func _ready():
+	get_viewport().size_changed.connect(resize_ui)
+	resize_ui()
+	respawn()
+
+func _physics_process(delta):
+	if health() < 1 or position.y <= -1000:
+		die()
+
+	if suspended:
+		return
+
+	# Backpack keys
+	do_backpack_keys()
+	# Movement
+	do_movement(delta)
+	# Use gears
+	do_gears()
+
 # Signals
 
 func _on_vanish_timer_timeout():
diff --git a/player/player.tscn b/player/player.tscn
index 3da27e3..10a0f29 100644
--- a/player/player.tscn
+++ b/player/player.tscn
@@ -93,7 +93,7 @@ vertical_alignment = 1
 wait_time = 4.0
 one_shot = true
 
-[node name="BackpackUI" type="Label" parent="."]
+[node name="HUD" type="Label" parent="."]
 offset_right = 200.0
 offset_bottom = 200.0
 text = "Pictures of you"
diff --git a/world/killbrick.gd b/world/killbrick.gd
index c587fe8..45f437b 100644
--- a/world/killbrick.gd
+++ b/world/killbrick.gd
@@ -2,4 +2,4 @@ extends Area3D
 
 func _on_body_entered(body: Node3D):
 	if body is Player:
-		body.health = 0
+		body.die()