Rework the UI on Crusenho's pack; credit it in the game, not just the repo

Crusenho's Complete UI Essential Pack is CC BY 4.0 -- redistributable and
commercial-friendly, confirmed from the License.txt the pack itself ships --
so unlike the two bdragon packs a subset is committed: twelve PNGs, 48 KB,
under assets/sprites/ui/. Only what is used, because each committed PNG costs
a Godot .import sidecar and a directory nothing references is one nobody
prunes.

UiTheme builds a Theme in code from it -- button states, panels, line edits --
and every screen roots itself through UiTheme.themed_root(). The HUD's bars are
the pack's frame with a tinted fill, drawn as three horizontal slices because
Godot's nine-patch lives on nodes and the HUD is drawn rather than built from
controls. Inventory slots use the pack's slot art at exactly twice the source
size; a non-integer scale on a 1px border reads as a wobble along every edge.

The credits screen is the other half of the request and it is a licence
obligation, not a nicety: two packs are now CC BY, which asks for attribution
"in any reasonable manner", and a markdown file in a source repo is not
reasonable for someone who downloaded a build. Settings -> Credits shows every
source with its terms and a link to the licence text. test_credits.gd asserts
CREDITS.md and docs/ASSETS.md name every entry, so the three cannot drift.

Two things found by actually looking at the screen, which is the point:

  - The FIRST version of this styled nothing. A Control inherits its theme from
    Control ANCESTORS only, and the chain breaks at the first plain Node or
    CanvasLayer -- which is every screen here. get_window().theme set the
    property, changed nothing, and read as correct. check.sh, 458 tests and a
    clean smoke run all passed with the entire interface unstyled. The theme
    test now instantiates every screen and asks what its buttons resolve.
  - The settings screen showed Fire bound to the right mouse button, because
    the test suite was writing the player's real user://settings.cfg --
    rebinding calls save() and nothing had redirected the path. Settings.path
    is now redirectable, the fixture points it at a scratch file, and a test
    asserts the default is still the player's own.

tools/screenshot.tscn is what found both. It boots the client windowed and
saves the menus, the HUD, settings and credits. Manual, needs a display, and
the only thing in the project that can tell you the interface rendered.

check.sh clean, 460 tests, SMOKE PASS, all four diagnostics green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/core/credits.gd

@@ -0,0 +1,76 @@
+class_name Credits
+extends RefCounted
+## Every third-party asset the game ships, and the terms it ships under.
+##
+## This is not decoration. Two of these packs are CC BY 4.0, which requires
+## attribution "in any reasonable manner" -- a file in the repository is not
+## reasonable for a player who downloaded a build, so the game has to say so
+## itself. See [CreditsScreen].
+##
+## `tests/unit/test_credits.gd` asserts every entry here also appears in
+## CREDITS.md, so the two cannot drift apart.
+
+## Each entry: what it is, who made it, the licence, a link, and what it is
+## used for. `required` marks the ones the licence obliges us to show.
+const SOURCES: Array[Dictionary] = [
+	{
+		"name": "16x16 DungeonTileset II",
+		"author": "0x72 (Robert Norenberg)",
+		"licence": "CC0 1.0 (public domain)",
+		"url": "https://0x72.itch.io/dungeontileset-ii",
+		"used_for": "Terrain, characters, bosses, item icons",
+		"required": false,
+	},
+	{
+		"name": "Complete UI Essential Pack",
+		"author": "Crusenho Agus Hennihuno",
+		"licence": "CC BY 4.0",
+		"url": "https://crusenho.itch.io/complete-ui-essential-pack",
+		"used_for": "Buttons, panels, bars, inventory slots",
+		"required": true,
+	},
+	{
+		"name": "Pixel Combat SFX",
+		"author": "Helton Yan",
+		"licence": "CC BY 4.0",
+		"url": "https://heltonyan.itch.io/pixelcombat",
+		"used_for": "All sound effects",
+		"required": true,
+	},
+	{
+		"name": "Fire Pixel Bullet 16x16",
+		"author": "bdragon1727",
+		"licence": "Custom - not redistributable",
+		"url": "https://bdragon1727.itch.io/fire-pixel-bullet-16x16",
+		"used_for": "Bullet sprites (local builds only)",
+		"required": false,
+	},
+	{
+		"name": "750+ Effect and FX Pixel All",
+		"author": "bdragon1727",
+		"licence": "Custom - not redistributable",
+		"url": "https://bdragon1727.itch.io/750-effect-and-fx-pixel-all",
+		"used_for": "Impact effects (local builds only)",
+		"required": false,
+	},
+]
+
+## CC BY asks for a link to the licence itself, not only to the work.
+const LICENCE_LINKS := {
+	"CC BY 4.0": "https://creativecommons.org/licenses/by/4.0/",
+	"CC0 1.0 (public domain)": "https://creativecommons.org/publicdomain/zero/1.0/",
+}
+
+
+## The packs whose licence actually obliges us to credit them. Everything else
+## in [constant SOURCES] is there because the work deserves it.
+static func required() -> Array[Dictionary]:
+	var out: Array[Dictionary] = []
+	for entry in SOURCES:
+		if bool(entry["required"]):
+			out.append(entry)
+	return out
+
+
+static func licence_url(licence: String) -> String:
+	return String(LICENCE_LINKS.get(licence, ""))

src/core/credits.gd.uid

@@ -0,0 +1 @@
+uid://drpadmmsrvoax

src/core/settings.gd

@@ -10,7 +10,14 @@ extends RefCounted
 ## tool has no main loop and cannot resolve autoload names, and the settings
 ## file is something a headless test may well want to read.
 
-const PATH := "user://settings.cfg"
+const DEFAULT_PATH := "user://settings.cfg"
+
+## Where preferences are read from and written to. A variable rather than a
+## constant so tests can point it at a scratch file: rebinding calls save(),
+## and a suite run was otherwise rewriting the player's real settings -- which
+## it did, silently, until a screenshot showed Fire bound to the right mouse
+## button.
+static var path: String = DEFAULT_PATH
 
 ## Actions the settings screen offers, in the order it lists them. Anything not
 ## here keeps whatever `tools/setup_input_map.gd` gave it and cannot be changed
@@ -54,7 +61,7 @@ static var _defaults_captured: bool = false
 static func load_and_apply() -> void:
 	_capture_defaults()
 	var cfg := ConfigFile.new()
-	if cfg.load(PATH) == OK:
+	if cfg.load(path) == OK:
 		master_volume = clampf(float(cfg.get_value("audio", "master", master_volume)), 0.0, 1.0)
 		sfx_volume = clampf(float(cfg.get_value("audio", "sfx", sfx_volume)), 0.0, 1.0)
 		bindings.clear()
@@ -81,9 +88,9 @@ static func save() -> void:
 	cfg.set_value("audio", "sfx", sfx_volume)
 	for action in bindings:
 		cfg.set_value("input", action, bindings[action])
-	var err := cfg.save(PATH)
+	var err := cfg.save(path)
 	if err != OK:
-		GameLog.warn("settings", "could not write %s (error %d)" % [PATH, err])
+		GameLog.warn("settings", "could not write %s (error %d)" % [path, err])
 
 
 # --- Audio -------------------------------------------------------------------

src/game.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=10 format=3]
+[gd_scene load_steps=11 format=3]
 
 [ext_resource type="Script" path="res://src/view/game_scene.gd" id="1"]
 [ext_resource type="Script" path="res://src/view/world_view.gd" id="2"]
@@ -9,6 +9,7 @@
 [ext_resource type="Script" path="res://src/ui/character_select.gd" id="7"]
 [ext_resource type="Script" path="res://src/ui/upgrade_screen.gd" id="8"]
 [ext_resource type="Script" path="res://src/ui/settings_screen.gd" id="9"]
+[ext_resource type="Script" path="res://src/ui/credits_screen.gd" id="10"]
 
 [node name="Game" type="Node2D"]
 script = ExtResource("1")
@@ -37,3 +38,6 @@ script = ExtResource("8")
 
 [node name="SettingsScreen" type="CanvasLayer" parent="."]
 script = ExtResource("9")
+
+[node name="CreditsScreen" type="CanvasLayer" parent="."]
+script = ExtResource("10")

src/main.gd

@@ -11,6 +11,7 @@ const CONNECT_TIMEOUT_SEC := 8.0
 
 var _menu: Control = null
 var _settings: CanvasLayer = null
+var _credits: CanvasLayer = null
 var _game: Node = null
 var _ticks: int = 0
 var _connecting: bool = false
@@ -151,10 +152,19 @@ func _open_settings() -> void:
 	if _settings == null:
 		_settings = preload("res://src/ui/settings_screen.gd").new()
 		_settings.closed.connect(func() -> void: _settings.visible = false)
+		_settings.credits_requested.connect(_open_credits)
 		add_child(_settings)
 	_settings.open()
 
 
+func _open_credits() -> void:
+	if _credits == null:
+		_credits = preload("res://src/ui/credits_screen.gd").new()
+		_credits.closed.connect(func() -> void: _credits.visible = false)
+		add_child(_credits)
+	_credits.open()
+
+
 func _clear_game() -> void:
 	if _game != null:
 		_game.queue_free()

src/ui/character_select.gd

@@ -24,8 +24,7 @@ var _selected: String = ""
 func _ready() -> void:
 	layer = 30
 	_rng.randomize()
-	var root := Control.new()
-	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	var root := UiTheme.themed_root()
 	add_child(root)
 
 	var scrim := ColorRect.new()

src/ui/credits_screen.gd

@@ -0,0 +1,94 @@
+extends CanvasLayer
+## Attribution, in the game rather than only in the repository.
+##
+## CC BY 4.0 requires credit "in any reasonable manner", and a markdown file
+## nobody who downloads a build will ever see does not clear that bar. Two of
+## the packs the game ships are CC BY, so this screen is a licence obligation
+## and not a nicety -- which is why its contents come from [Credits] and a test
+## asserts nothing in there is missing from it.
+
+signal closed
+
+var _list: VBoxContainer
+
+
+func _ready() -> void:
+	layer = 34
+	visible = false
+	var root := UiTheme.themed_root()
+	add_child(root)
+
+	var scrim := ColorRect.new()
+	scrim.color = Color(0.03, 0.03, 0.06, 0.95)
+	scrim.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	scrim.mouse_filter = Control.MOUSE_FILTER_STOP
+	root.add_child(scrim)
+
+	var centre := CenterContainer.new()
+	centre.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	root.add_child(centre)
+
+	var panel := VBoxContainer.new()
+	panel.custom_minimum_size = Vector2(620.0, 0.0)
+	panel.add_theme_constant_override("separation", 8)
+	centre.add_child(panel)
+
+	var title := Label.new()
+	title.text = "CREDITS"
+	title.add_theme_font_size_override("font_size", 26)
+	panel.add_child(title)
+
+	var intro := Label.new()
+	intro.text = "Third-party work this game is built from. " \
+		+ "Credited whether or not the licence asks."
+	intro.add_theme_font_size_override("font_size", 12)
+	intro.add_theme_color_override("font_color", Color(0.6, 0.65, 0.78))
+	intro.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	intro.custom_minimum_size = Vector2(620.0, 0.0)
+	panel.add_child(intro)
+
+	var scroll := ScrollContainer.new()
+	scroll.custom_minimum_size = Vector2(620.0, 340.0)
+	panel.add_child(scroll)
+	_list = VBoxContainer.new()
+	_list.custom_minimum_size = Vector2(600.0, 0.0)
+	_list.add_theme_constant_override("separation", 12)
+	scroll.add_child(_list)
+	for entry in Credits.SOURCES:
+		_add_entry(entry)
+
+	var close := Button.new()
+	close.text = "Close"
+	close.custom_minimum_size = Vector2(160.0, 34.0)
+	close.pressed.connect(func() -> void: closed.emit())
+	panel.add_child(close)
+
+
+func _add_entry(entry: Dictionary) -> void:
+	var block := VBoxContainer.new()
+	block.add_theme_constant_override("separation", 1)
+	_list.add_child(block)
+
+	var heading := Label.new()
+	heading.text = "%s  —  %s" % [entry["name"], entry["author"]]
+	heading.add_theme_font_size_override("font_size", 16)
+	block.add_child(heading)
+
+	var detail := Label.new()
+	var licence := String(entry["licence"])
+	var link := Credits.licence_url(licence)
+	# The licence LINK, not just its name: CC BY asks for one, and a player
+	# reading this screen has no other way to reach the terms.
+	detail.text = "%s  ·  %s%s\n%s" % [
+		entry["used_for"], licence,
+		"  ·  " + link if not link.is_empty() else "",
+		entry["url"]]
+	detail.add_theme_font_size_override("font_size", 12)
+	detail.add_theme_color_override("font_color", Color(0.62, 0.67, 0.8))
+	detail.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	detail.custom_minimum_size = Vector2(600.0, 0.0)
+	block.add_child(detail)
+
+
+func open() -> void:
+	visible = true

src/ui/credits_screen.gd.uid

@@ -0,0 +1 @@
+uid://bo3xikvfahke5

src/ui/game_menu.gd

@@ -23,8 +23,7 @@ var _open: bool = false
 
 func _ready() -> void:
 	layer = 20
-	var root := Control.new()
-	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	var root := UiTheme.themed_root()
 	add_child(root)
 
 	# Dim the game behind the menu so it is obvious the world is still running.

src/ui/hud.gd

@@ -6,8 +6,17 @@ const MARGIN := 24.0
 const BAR_W := 260.0
 const BAR_H := 16.0
 ## Inventory slot box, and the gap between boxes.
-const SLOT := 46.0
+##
+## Exactly twice the 32px source sprite. A non-integer scale on pixel art with
+## nearest filtering gives uneven pixel widths, which on a 1px border reads as
+## a wobble along the edge of every slot.
+const SLOT := 64.0
 const SLOT_GAP := 8.0
+## Source-pixel width of the caps on the bar sprite. The bar is stretched only
+## horizontally, so the ends are drawn at their own size and the middle takes
+## whatever is left -- a plain stretched draw would smear a 1px border out to
+## eight.
+const BAR_CAP := 6.0
 ## How far above the bottom of the screen the inventory row sits.
 const SLOT_BOTTOM := 26.0
 
@@ -31,6 +40,7 @@ func _ready() -> void:
 	# and the death-message centering down with it, since all three read
 	# _canvas.size. set_anchors_and_offsets_preset() sets both correctly.
 	_canvas.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	UiTheme.apply_to(_canvas)
 	_canvas.mouse_filter = Control.MOUSE_FILTER_IGNORE
 	_canvas.draw.connect(_draw_hud)
 	add_child(_canvas)
@@ -44,7 +54,10 @@ func _ready() -> void:
 	# here means "56px above the bottom anchor", which is what "-56" was meant
 	# to say in the first place.
 	_hint.offset_left = MARGIN
-	_hint.offset_top = -56.0
+	# Above the inventory row, not through it. Derived from the row's own
+	# geometry rather than written down, because the slots grew from 46px to 64
+	# and a hardcoded -56 put the control hints straight across them.
+	_hint.offset_top = -(SLOT_BOTTOM + SLOT + 34.0)
 
 	# A real Button rather than something drawn in _draw_hud: this is the one
 	# HUD element the player has to actually click, and it starts disabled so
@@ -126,13 +139,13 @@ func _draw_hud() -> void:
 	var origin := Vector2(MARGIN, MARGIN + 28.0)
 	_bar(origin, float(client.my_hp) / float(maxi(client.my_max_hp, 1)),
 		Color(0.35, 0.9, 0.6), Color(0.1, 0.15, 0.18))
-	_draw_xp_bar(origin + Vector2(0.0, BAR_H + 3.0))
+	_draw_xp_bar(origin + Vector2(0.0, BAR_H + 4.0))
 
 	if client.my_escaping:
-		_bar(origin + Vector2(0.0, BAR_H + 8.0), client.my_escape,
+		_bar(origin + Vector2(0.0, (BAR_H + 4.0) * 2.0), client.my_escape,
 			Color(0.5, 0.85, 1.0), Color(0.1, 0.15, 0.2))
 		_canvas.draw_string(ThemeDB.fallback_font,
-			origin + Vector2(BAR_W + 12.0, BAR_H + 8.0 + BAR_H),
+			origin + Vector2(BAR_W + 12.0, (BAR_H + 4.0) * 2.0 + BAR_H - 3.0),
 			"ESCAPING", HORIZONTAL_ALIGNMENT_LEFT, -1, 14, Color(0.5, 0.85, 1.0))
 
 	_draw_boss_bar()
@@ -195,15 +208,15 @@ func _draw_inventory() -> void:
 		var at := origin + Vector2(float(i) * (SLOT + SLOT_GAP), 0.0)
 		var item := Items.by_index(int(client.my_inventory[i]))
 		var def := Items.get_def(item)
-		var frame_col := Color(0.55, 0.6, 0.72, 0.75) if i == held \
-			else Color(0.3, 0.33, 0.42, 0.6)
-		_canvas.draw_rect(Rect2(at, Vector2(SLOT, SLOT)), Color(0.07, 0.08, 0.12, 0.72))
-		_canvas.draw_rect(Rect2(at, Vector2(SLOT, SLOT)), frame_col, false, 1.5)
+		# The held slot uses the pack's pressed-in slot art rather than a
+		# recoloured border, so "this is the one the key is on" reads the same
+		# way every other pressed thing in the interface does.
+		var slot_art := UiTheme.texture("slot_active" if i == held else "slot")
+		_canvas.draw_texture_rect(slot_art, Rect2(at, Vector2(SLOT, SLOT)), false)
 		# The slot number, because the key that uses it is the only thing the
 		# player actually needs to know about a slot.
-		_canvas.draw_string(ThemeDB.fallback_font, at + Vector2(4.0, 13.0),
-			str(i + 1), HORIZONTAL_ALIGNMENT_LEFT, -1, 11,
-			Color(0.5, 0.55, 0.68))
+		_canvas.draw_string(ThemeDB.fallback_font, at + Vector2(6.0, 17.0),
+			str(i + 1), HORIZONTAL_ALIGNMENT_LEFT, -1, 12, UiTheme.INK_DIM)
 		if def == null:
 			continue
 		var icon := Art.item_icon(item)
@@ -248,13 +261,12 @@ func _draw_xp_bar(at: Vector2) -> void:
 	var capped := level >= Progression.MAX_LEVEL
 	var progress := Progression.level_progress(client.my_total_xp)
 	var tint := Color(1.0, 0.85, 0.4) if capped else Color(0.6, 0.55, 1.0)
-	_canvas.draw_rect(Rect2(at, Vector2(BAR_W, 5.0)), Color(0.1, 0.12, 0.18))
-	_canvas.draw_rect(Rect2(at, Vector2(BAR_W * progress, 5.0)), tint)
+	_bar(at, progress, tint, Color.BLACK)
 	# The number as well as the bar: "how far to the next level" is a question
 	# a bar answers vaguely and a percentage answers exactly.
 	var text := "MAX" if capped else "%d%% to level %d" % [
 		int(floor(progress * 100.0)), level + 1]
-	_canvas.draw_string(ThemeDB.fallback_font, at + Vector2(BAR_W + 10.0, 6.0),
+	_canvas.draw_string(ThemeDB.fallback_font, at + Vector2(BAR_W + 10.0, 13.0),
 		text, HORIZONTAL_ALIGNMENT_LEFT, -1, 12, tint)
 
 
@@ -299,8 +311,13 @@ func _draw_boss_bar() -> void:
 	var w := 560.0
 	var pos := Vector2((_canvas.size.x - w) * 0.5, MARGIN)
 	var frac := clampf(float(b["hp"]) / float(client.boss_def.max_hp), 0.0, 1.0)
-	_canvas.draw_rect(Rect2(pos, Vector2(w, BAR_H)), Color(0.12, 0.08, 0.1))
-	_canvas.draw_rect(Rect2(pos, Vector2(w * frac, BAR_H)), Color(0.95, 0.35, 0.45))
+	var rect := Rect2(pos, Vector2(w, BAR_H))
+	_hslice(UiTheme.texture("bar"), rect, Color.WHITE)
+	var inner := Rect2(rect.position + Vector2(3.0, 3.0),
+		Vector2((w - 6.0) * frac, BAR_H - 6.0))
+	if inner.size.x > 0.5:
+		_canvas.draw_texture_rect(UiTheme.texture("bar_fill"), inner, false,
+			Color(0.95, 0.35, 0.45))
 	var phase_index := int(b["phase"])
 	var phase_name := ""
 	if phase_index < client.boss_def.phases.size():
@@ -310,9 +327,45 @@ func _draw_boss_bar() -> void:
 		HORIZONTAL_ALIGNMENT_LEFT, -1, 14, Color(1.0, 0.75, 0.8))
 
 
-func _bar(pos: Vector2, frac: float, fill: Color, back: Color) -> void:
-	_canvas.draw_rect(Rect2(pos, Vector2(BAR_W, BAR_H)), back)
-	_canvas.draw_rect(Rect2(pos, Vector2(BAR_W * clampf(frac, 0.0, 1.0), BAR_H)), fill)
+## A bar in the pack's art: the frame stretched horizontally, the fill tinted.
+##
+## [param back] is no longer a colour -- the frame sprite is the background --
+## but the signature keeps it so callers read the same and a future flat-bar
+## fallback has somewhere to go.
+func _bar(pos: Vector2, frac: float, fill: Color, _back: Color) -> void:
+	var rect := Rect2(pos, Vector2(BAR_W, BAR_H))
+	_hslice(UiTheme.texture("bar"), rect, Color.WHITE)
+	var inset := 3.0
+	var inner := Rect2(rect.position + Vector2(inset, inset),
+		Vector2((rect.size.x - inset * 2.0) * clampf(frac, 0.0, 1.0),
+			rect.size.y - inset * 2.0))
+	if inner.size.x > 0.5:
+		# The fill sprite is a flat strip, so tinting it is the whole palette --
+		# one texture covers health, experience, the escape channel and the
+		# boss.
+		_canvas.draw_texture_rect(UiTheme.texture("bar_fill"), inner, false, fill)
+
+
+## Draw a horizontally stretchable sprite as three slices: left cap, stretched
+## middle, right cap. Godot's nine-patch lives on nodes rather than on the
+## immediate-mode API, and the HUD is drawn rather than built out of controls.
+func _hslice(tex: Texture2D, rect: Rect2, tint: Color) -> void:
+	if tex == null:
+		return
+	var src := Vector2(tex.get_size())
+	var cap := minf(BAR_CAP, src.x * 0.5)
+	var draw_cap := cap * (rect.size.y / src.y)
+	_canvas.draw_texture_rect_region(tex,
+		Rect2(rect.position, Vector2(draw_cap, rect.size.y)),
+		Rect2(0.0, 0.0, cap, src.y), tint)
+	_canvas.draw_texture_rect_region(tex,
+		Rect2(rect.position + Vector2(draw_cap, 0.0),
+			Vector2(maxf(rect.size.x - draw_cap * 2.0, 0.0), rect.size.y)),
+		Rect2(cap, 0.0, src.x - cap * 2.0, src.y), tint)
+	_canvas.draw_texture_rect_region(tex,
+		Rect2(rect.position + Vector2(rect.size.x - draw_cap, 0.0),
+			Vector2(draw_cap, rect.size.y)),
+		Rect2(src.x - cap, 0.0, cap, src.y), tint)
 
 
 func flash_hit() -> void:

src/ui/main_menu.gd

@@ -24,6 +24,7 @@ func _ready() -> void:
 	# what actually caused the "menu stuck in the top-left corner" bug --
 	# set_anchors_and_offsets_preset() sets both halves correctly in one call.
 	set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	UiTheme.apply_to(self)
 
 	# A CenterContainer recomputes its child's centered position itself, every
 	# time the child's minimum size or the window size changes -- no manual

src/ui/settings_screen.gd

@@ -6,6 +6,7 @@ extends CanvasLayer
 ## game's state that should change what it can do.
 
 signal closed
+signal credits_requested
 
 var _rows: Dictionary[String, Button] = {}
 var _status: Label
@@ -20,8 +21,7 @@ var _listening: String = ""
 func _ready() -> void:
 	layer = 32
 	visible = false
-	var root := Control.new()
-	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	var root := UiTheme.themed_root()
 	add_child(root)
 
 	var scrim := ColorRect.new()
@@ -81,6 +81,11 @@ func _ready() -> void:
 		_status.text = "controls reset"
 		refresh())
 	buttons.add_child(reset)
+	var credits := Button.new()
+	credits.text = "Credits"
+	credits.custom_minimum_size = Vector2(160.0, 34.0)
+	credits.pressed.connect(func() -> void: credits_requested.emit())
+	buttons.add_child(credits)
 	var close := Button.new()
 	close.text = "Close"
 	close.custom_minimum_size = Vector2(160.0, 34.0)

src/ui/upgrade_screen.gd

@@ -31,8 +31,7 @@ var _status: Label
 func _ready() -> void:
 	layer = 28
 	visible = false
-	var root := Control.new()
-	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	var root := UiTheme.themed_root()
 	add_child(root)
 
 	var scrim := ColorRect.new()

src/view/game_scene.gd

@@ -10,6 +10,7 @@ extends Node2D
 @onready var characters: CanvasLayer = $CharacterSelect
 @onready var upgrades: CanvasLayer = $UpgradeScreen
 @onready var settings: CanvasLayer = $SettingsScreen
+@onready var credits: CanvasLayer = $CreditsScreen
 
 var _bound: ClientRuntime = null
 ## Opened deliberately from the menu, as opposed to forced open by having no
@@ -37,6 +38,8 @@ func _ready() -> void:
 	upgrades.closed.connect(func() -> void: _upgrades_open = false)
 	menu.settings_requested.connect(func() -> void: settings.open())
 	settings.closed.connect(func() -> void: settings.visible = false)
+	settings.credits_requested.connect(func() -> void: credits.open())
+	credits.closed.connect(func() -> void: credits.visible = false)
 	upgrades.choose_requested.connect(func(i: int) -> void: Net.choose_upgrade(i))
 
 

src/view/ui_theme.gd

@@ -0,0 +1,116 @@
+class_name UiTheme
+extends RefCounted
+## The game's control theme, built in code from Crusenho's UI pack.
+##
+## Built rather than authored as a .tres for the same reason [Content] is code:
+## it is a readable diff, there are no resource UIDs churning in version
+## control, and a test can build it without the editor.
+##
+## Applied to each screen's root Control ([method apply_to]). It cannot be
+## applied once to the Window instead: Godot's theme lookup walks a Control's
+## ancestors, and the chain BREAKS at the first plain Node -- which for every
+## screen here is `main.gd` or a CanvasLayer. Setting `window.theme` looked like
+## it worked and changed nothing.
+
+const DIR := "res://assets/sprites/ui/"
+
+## Every texture the theme needs. Named so a test can assert they all load: a
+## missing file gives a null texture and a silently unstyled control, which
+## looks like the theme never being applied at all.
+const TEXTURES := {
+	"button": DIR + "Button01a_1.png",
+	"button_hover": DIR + "Button01a_2.png",
+	"button_pressed": DIR + "Button01a_3.png",
+	"button_disabled": DIR + "Button01a_4.png",
+	"panel": DIR + "Frame01a.png",
+	"panel_accent": DIR + "Frame02a.png",
+	"slot": DIR + "FrameSlot01a.png",
+	"slot_active": DIR + "FrameSlot01b.png",
+	"bar": DIR + "Bar01a.png",
+	"bar_fill": DIR + "BarFill01f.png",
+	"field": DIR + "InputField01a.png",
+	"banner": DIR + "Banner01a.png",
+}
+
+## The art is cream with a black outline, so text on it has to be dark. Every
+## label the game draws over the dark world stays light; only controls that sit
+## on this pack's own surfaces flip.
+const INK := Color(0.12, 0.11, 0.13)
+const INK_DIM := Color(0.42, 0.40, 0.44)
+
+static var _theme: Theme = null
+
+
+static func texture(key: String) -> Texture2D:
+	return load(TEXTURES[key]) as Texture2D
+
+
+## One shared instance. Themes are pure data and every control only reads them,
+## so building a second would be waste rather than isolation.
+static func get_theme() -> Theme:
+	if _theme != null:
+		return _theme
+	var t := Theme.new()
+	t.default_font_size = 14
+
+	t.set_stylebox("normal", "Button", _box("button", 8, 12, 7))
+	t.set_stylebox("hover", "Button", _box("button_hover", 8, 12, 7))
+	t.set_stylebox("pressed", "Button", _box("button_pressed", 8, 12, 7))
+	t.set_stylebox("disabled", "Button", _box("button_disabled", 8, 12, 7))
+	# Focus deliberately reuses the hover art rather than adding an outline:
+	# the pack has no focus state, and an invented one would be the only thing
+	# on screen that is not from the set.
+	t.set_stylebox("focus", "Button", _box("button_hover", 8, 12, 7))
+	t.set_color("font_color", "Button", INK)
+	t.set_color("font_hover_color", "Button", INK)
+	t.set_color("font_pressed_color", "Button", INK)
+	t.set_color("font_disabled_color", "Button", INK_DIM)
+	t.set_color("font_focus_color", "Button", INK)
+
+	t.set_stylebox("panel", "Panel", _box("panel", 8, 10, 10))
+	t.set_stylebox("panel", "PanelContainer", _box("panel", 8, 10, 10))
+
+	t.set_stylebox("normal", "LineEdit", _box("field", 8, 10, 6))
+	t.set_stylebox("focus", "LineEdit", _box("field", 8, 10, 6))
+	t.set_color("font_color", "LineEdit", INK)
+	t.set_color("font_placeholder_color", "LineEdit", INK_DIM)
+	t.set_color("caret_color", "LineEdit", INK)
+
+	_theme = t
+	return _theme
+
+
+## Give [param root] the theme. Everything under it inherits, so one call per
+## screen covers that screen.
+##
+## Per-screen rather than once on the Window, because theme inheritance only
+## travels Control-to-Control: a Control whose parent is a plain Node or a
+## CanvasLayer resolves against the default theme however the Window is set.
+## Every screen in this game hangs off one or the other.
+static func apply_to(root: Control) -> void:
+	if root != null:
+		root.theme = get_theme()
+
+
+## A full-rect Control with the theme already on it -- the root every screen
+## built in code starts from. Using this rather than a bare Control is what
+## stops a new screen quietly rendering unstyled.
+static func themed_root() -> Control:
+	var root := Control.new()
+	root.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	apply_to(root)
+	return root
+
+
+## A nine-patch stylebox. [param margin] is the corner size in source pixels;
+## the middle is what stretches.
+static func _box(key: String, margin: int, pad_x: int, pad_y: int) -> StyleBoxTexture:
+	var sb := StyleBoxTexture.new()
+	sb.texture = texture(key)
+	for side in [SIDE_LEFT, SIDE_TOP, SIDE_RIGHT, SIDE_BOTTOM]:
+		sb.set_texture_margin(side, float(margin))
+	sb.set_content_margin(SIDE_LEFT, float(pad_x))
+	sb.set_content_margin(SIDE_RIGHT, float(pad_x))
+	sb.set_content_margin(SIDE_TOP, float(pad_y))
+	sb.set_content_margin(SIDE_BOTTOM, float(pad_y))
+	return sb

src/view/ui_theme.gd.uid

@@ -0,0 +1 @@
+uid://ddaj0c8xfjitx