Initial commit — Station 0 vertical slice in progress

Includes full design documentation (ARCHITECTURE, DESIGN_NOTES, CONTENT_SPEC, PRODUCTION_NOTES)
and active Godot 4 / GDScript codebase. Core systems built: player, floor generation,
room system, enemy base, body part upgrades, run manager, save system, HUD, EventBus.

scripts/upgrades/body_part_data.gd

@@ -0,0 +1,29 @@
+extends Resource
+class_name BodyPartData
+
+@export var slot:         String = ""   # "head" | "torso" | "left_arm" | "right_arm" | "legs"
+@export var display_name: String = ""
+
+# ---------------------------------------------------------------------------
+# Stat modifiers — additive bonuses stacked across all equipped parts.
+# Field names mirror the stat keys used in player_stats.gd.
+# ---------------------------------------------------------------------------
+@export var mod_speed:      float = 0.0
+@export var mod_max_health: float = 0.0
+@export var mod_damage:     float = 0.0
+@export var mod_fire_rate:  float = 0.0
+@export var mod_range:      float = 0.0
+@export var mod_proj_speed: float = 0.0   # flat delta; e.g. -104 = -20% of base 520
+
+# ---------------------------------------------------------------------------
+# Scatter (left arm slot)
+# mod_scatter_count > 0 enables multi-shot spread from this part
+# ---------------------------------------------------------------------------
+@export var mod_scatter_count:      int   = 0
+@export var mod_scatter_spread_deg: float = 0.0
+
+# ---------------------------------------------------------------------------
+# Shield Projector (left arm slot)
+# Active block on cooldown — absorbs one hit per activation
+# ---------------------------------------------------------------------------
+@export var shield_projector: bool = false

scripts/upgrades/body_part_pickup.gd

@@ -0,0 +1,11 @@
+extends Area2D
+
+var part: BodyPartData = null
+
+func _ready() -> void:
+	body_entered.connect(_on_body_entered)
+
+func _on_body_entered(body: Node) -> void:
+	if body.is_in_group("player") and part != null:
+		UpgradeManager.acquire_part(part)
+		queue_free()

scripts/upgrades/upgrade_manager.gd

@@ -0,0 +1,63 @@
+extends Node
+
+const SLOTS: Array[String] = ["head", "torso", "left_arm", "right_arm", "legs"]
+
+var hub_credits: int = 0
+
+# slot -> BodyPart resource path (empty string = default/base part)
+var equipped_parts: Dictionary = {
+	"head": "",
+	"torso": "",
+	"left_arm": "",
+	"right_arm": "",
+	"legs": "",
+}
+
+# All permanently acquired part resource paths
+var acquired_part_paths: Array[String] = []
+
+func equip_part(part: Resource) -> void:
+	var slot: String = part.slot
+	if slot not in SLOTS:
+		push_error("UpgradeManager: invalid slot '%s'" % slot)
+		return
+	equipped_parts[slot] = part.resource_path
+	EventBus.body_part_equipped.emit(part, slot)
+
+func acquire_part(part: Resource) -> void:
+	if part.resource_path not in acquired_part_paths:
+		acquired_part_paths.append(part.resource_path)
+	EventBus.body_part_found.emit(part)
+
+func get_equipped_part(slot: String) -> Resource:
+	var path: String = equipped_parts.get(slot, "")
+	if path != "":
+		return load(path)
+	return null
+
+func get_stat_modifier(stat: String) -> float:
+	var total := 0.0
+	for slot in SLOTS:
+		var part := get_equipped_part(slot)
+		if part == null:
+			continue
+		match stat:
+			"speed":      total += part.mod_speed
+			"max_health": total += part.mod_max_health
+			"damage":     total += part.mod_damage
+			"fire_rate":  total += part.mod_fire_rate
+			"range":      total += part.mod_range
+			"proj_speed": total += part.mod_proj_speed
+	return total
+
+func get_save_data() -> Dictionary:
+	return {
+		"equipped": equipped_parts.duplicate(),
+		"acquired": acquired_part_paths.duplicate(),
+	}
+
+func load_save_data(data: Dictionary) -> void:
+	var saved_equipped: Dictionary = data.get("equipped", {})
+	for slot in SLOTS:
+		equipped_parts[slot] = saved_equipped.get(slot, "")
+	acquired_part_paths = data.get("acquired", [])