===================================================================
--- original.js
+++ change.js
@@ -5,23 +5,26 @@
 
 /**** 
 * Classes
 ****/ 
+/**** 
+* CLASSES
+****/ 
 /** 
 * A cluster container that spawns several Ore objects of the same type.
 * We track how many remain. Once all are destroyed, we remove the cluster
-* container from the game, then after a delay, spawn a new cluster if allowed.
+* and eventually spawn a new one (after a delay).
 */ 
 var Cluster = Container.expand(function (type) {
 	var self = Container.call(this);
 	self.type = type;
-	self.oreList = []; // the Ore objects in this cluster
+	self.oreList = [];
 	// Random center
 	var centerX = 100 + Math.random() * (2048 - 200);
 	var centerY = 100 + Math.random() * (2732 - 200);
 	self.x = centerX;
 	self.y = centerY;
-	// Decide how many ore are in this cluster, based on the cluster config
+	// Decide how many ore are in this cluster
 	var clusterConfig = gameState.clusterConfig;
 	var count = randomInt(clusterConfig.min, clusterConfig.max);
 	// Create each ore with random offsets
 	for (var i = 0; i < count; i++) {
@@ -30,51 +33,38 @@
 		ore.y = (Math.random() - 0.5) * 120;
 		self.oreList.push(ore);
 		self.addChild(ore);
 	}
-	// Called when an ore is destroyed
 	self.notifyOreDestroyed = function (ore) {
-		// remove from the container
 		if (self.oreList.indexOf(ore) >= 0) {
 			self.oreList.splice(self.oreList.indexOf(ore), 1);
 		}
 		ore.destroy();
-		// If all ore gone => cluster is done
+		// If all gone => cluster done
 		if (self.oreList.length === 0) {
-			// remove cluster from stage
 			if (self.parent) {
 				self.parent.removeChild(self);
 			}
-			// remove from global array
 			var idx = clusters.indexOf(self);
 			if (idx >= 0) {
 				clusters.splice(idx, 1);
 			}
 			// Decrement cluster count
 			gameState.clusterCount[self.type]--;
-			// Wait for respawnTime, then spawn a new cluster if not exceeding max
-			// If type == 'coal', we slow it further, e.g. 2x
+			// Wait, then spawn new cluster if not max
 			var finalDelay = gameState.respawnTime;
 			if (self.type === 'coal') {
-				finalDelay *= 2; // slow rate for coal
+				finalDelay *= 2; // slower for coal
 			}
 			LK.setTimeout(function () {
 				maybeSpawnCluster(self.type);
 			}, finalDelay);
 		}
 	};
 	return self;
 });
-/**** 
-* HELPER / UTILITY FUNCTIONS
-****/ 
-// Spawns a new cluster if we haven't reached max for that type
-/**** 
-* CLASSES
-****/ 
 /** 
-* Miner class: Moves to the closest available ore (within currentTier)
-* and mines it.
+* Miner class: moves to the closest available ore (within currentTier) and mines it.
 */ 
 var Miner = Container.expand(function () {
 	var self = Container.call(this);
 	self.attachAsset('miner', {
@@ -101,9 +91,9 @@
 		if (validOre.length === 0) {
 			self.currentTarget = null;
 			return;
 		}
-		// Calculate distance using ore's global coords: ore.parent.x + ore.x
+		// global coords
 		self.currentTarget = validOre.sort(function (a, b) {
 			var aX = a.parent.x + a.x;
 			var aY = a.parent.y + a.y;
 			var bX = b.parent.x + b.x;
@@ -115,9 +105,8 @@
 	};
 	self.update = function () {
 		self.findNewTarget();
 		if (self.currentTarget) {
-			// Global coords for the current target
 			var tx = self.currentTarget.parent.x + self.currentTarget.x;
 			var ty = self.currentTarget.parent.y + self.currentTarget.y;
 			var dx = tx - self.x;
 			var dy = ty - self.y;
@@ -128,30 +117,25 @@
 			} else {
 				self.mineOre(self.currentTarget);
 			}
 		} else {
-			// idle "hover"
+			// idle float
 			self.y += Math.sin(LK.time.elapsed / 250) * 0.5;
 		}
 	};
 	self.mineOre = function (ore) {
 		if (self.miningCooldown > 0) {
 			self.miningCooldown--;
 			return;
 		}
-		// apply damage
 		ore.health -= self.miningDamage * gameState.pickaxeLevel;
 		self.miningCooldown = self.miningRate;
-		// if destroyed
 		if (ore.health <= 0) {
 			gameState.money += ore.getValue();
 			updateUI();
-			// Remove from its cluster
 			ore.cluster.notifyOreDestroyed(ore);
-			// Particles
 			spawnMiningParticles(ore, 5);
 		} else {
-			// Particles for each hit
 			spawnMiningParticles(ore, 2);
 		}
 	};
 	return self;
@@ -162,28 +146,25 @@
 var Ore = Container.expand(function (type, cluster) {
 	var self = Container.call(this);
 	self.type = type;
 	self.cluster = cluster;
-	// Tier determination
+	// Tier
 	self.tier = ['coal', 'iron', 'gold', 'diamond'].indexOf(type) + 1;
-	self.maxHealth = 10; // fixed
+	self.maxHealth = 10;
 	self.health = self.maxHealth;
-	// Base value depends on tier
-	self.baseValue = 5 * self.tier;
-	// Attach sprite
+	self.baseValue = 5 * self.tier; // base money
 	self.attachAsset(type + '_ore', {
 		anchorX: 0.5,
 		anchorY: 0.5
 	});
-	// Larger health bar, properly centered above the ore (120×20)
+	// health bar: 120×20
 	self.healthBar = LK.getAsset('rectangle', {
 		width: 120,
 		height: 20,
 		fill: 0x00FF00,
 		anchorX: 0.5,
 		anchorY: 0.5
 	});
-	// Position above ore
 	self.healthBar.x = 0;
 	self.healthBar.y = -70;
 	self.addChild(self.healthBar);
 	self.getValue = function () {
@@ -195,8 +176,11 @@
 /**** 
 * Initialize Game
 ****/ 
 /**** 
+* HELPER / UTILITY FUNCTIONS
+****/ 
+/**** 
 * THE GAME
 ****/ 
 var game = new LK.Game({
 	backgroundColor: 0x1a1a1a
@@ -204,45 +188,43 @@
 
 /**** 
 * Game Code
 ****/ 
-// We'll store references to cluster containers (one container per cluster).
 /**** 
 * GLOBAL ARRAYS & STATE
 ****/ 
 /**** 
 * PLUGINS
 ****/ 
+// NEW asset for opening the shop:
+// Existing assets
 /**** 
 * ASSETS
 ****/ 
-var clusters = [];
-/**** 
-* GAME STATE
-****/ 
+// The Miner
+var clusters = []; // containers for each "cluster" of ore
 var gameState = {
 	money: 0,
 	pickaxeLevel: 1,
 	currentTier: 1,
-	// Multipliers for each ore type
 	oreMultipliers: {
 		coal: 1,
 		iron: 1,
 		gold: 1,
 		diamond: 1
 	},
 	// Respawn timing (in ms)
 	respawnTime: 3000,
-	// Max clusters (per type) at once
+	// Max # of clusters per type
 	maxClustersPerType: 3,
-	// Track how many clusters of each type currently exist on screen
+	// Currently existing cluster count by type
 	clusterCount: {
 		coal: 0,
 		iron: 0,
 		gold: 0,
 		diamond: 0
 	},
-	// Cluster range configs
+	// Config for cluster sizes
 	clusterConfigLevels: [{
 		min: 2,
 		max: 3
 	},
@@ -258,8 +240,9 @@
 		max: 10
 	}],
 	clusterUpgradeTier: 0,
 	get clusterConfig() {
+		// e.g. clusterConfigLevels[0] => 2-3
 		return this.clusterConfigLevels[this.clusterUpgradeTier] || {
 			min: 2,
 			max: 3
 		};
@@ -267,52 +250,37 @@
 };
 /**** 
 * HELPER / UTILITY FUNCTIONS
 ****/ 
-// Spawns a new cluster if we haven't reached max for that type
 function maybeSpawnCluster(type) {
-	// Tier check: don't spawn if locked
 	var tIndex = ['coal', 'iron', 'gold', 'diamond'].indexOf(type) + 1;
 	if (tIndex > gameState.currentTier) {
 		return;
 	}
-	// Check if we have space for a new cluster
 	if (gameState.clusterCount[type] >= gameState.maxClustersPerType) {
-		// do nothing, we've reached max
 		return;
 	}
-	// spawn a cluster
 	var cluster = new Cluster(type);
 	game.addChild(cluster);
 	clusters.push(cluster);
-	// increment cluster count
 	gameState.clusterCount[type]++;
 }
-// Random int between min and max inclusive
+// random int in [min, max]
 function randomInt(min, max) {
 	return Math.floor(Math.random() * (max - min + 1)) + min;
 }
-// Particle effect for mining
+// spawn mining particles
 function spawnMiningParticles(ore, num) {
 	for (var i = 0; i < num; i++) {
 		var p = LK.getAsset('mining_particle', {
 			anchorX: 0.5,
 			anchorY: 0.5
 		});
-		// Because ore is inside a cluster container
-		if (ore.parent) {
-			p.lastX = ore.parent.x + ore.x;
-			p.lastY = ore.parent.y + ore.y;
-		} else {
-			p.lastX = ore.x; // Fallback if parent is undefined 
-			p.lastY = ore.y;
-		}
-		p.x = p.lastX;
-		p.y = p.lastY;
+		p.x = ore.parent.x + ore.x;
+		p.y = ore.parent.y + ore.y;
 		p.vx = (Math.random() - 0.5) * 10;
 		p.vy = (Math.random() - 0.5) * 10;
 		p.alpha = 1;
-		// tween out
 		tween(p, {
 			alpha: 0,
 			y: p.y - 50
 		}, {
@@ -323,9 +291,9 @@
 		});
 		game.addChild(p);
 	}
 }
-// Color interpolation
+// color interpolation
 function interpolateColor(color1, color2, factor) {
 	var r1 = color1 >> 16 & 0xff;
 	var g1 = color1 >> 8 & 0xff;
 	var b1 = color1 & 0xff;
@@ -347,9 +315,11 @@
 });
 background.x = 2048 / 2;
 background.y = 2732 / 2;
 game.addChildAt(background, 0);
-// UI
+/**** 
+* UI
+****/ 
 var upgradeMenu = new Container();
 var tooltip = new Text2('', {
 	size: 40,
 	fill: 0xFFFFFF
@@ -362,272 +332,363 @@
 	strokeThickness: 5
 });
 moneyDisplay.x = 2048 / 2 - moneyDisplay.width / 2;
 moneyDisplay.y = 50;
-var shopButton = LK.getAsset('buy_button', {
+game.addChild(moneyDisplay);
+var shopOpenButton = LK.getAsset('shop_icon', {
+	// new asset
 	anchorX: 0.5,
 	anchorY: 0.5
 });
-shopButton.x = 2048 - 150;
-shopButton.y = 2732 - 150;
-shopButton.down = function () {
-	createUpgradeMenu();
+shopOpenButton.x = 2048 - 150;
+shopOpenButton.y = 2732 - 150;
+shopOpenButton.down = function () {
+	createMainUpgradeMenu();
 	game.addChild(upgradeMenu);
 };
-game.addChild(moneyDisplay);
-game.addChild(shopButton);
+game.addChild(shopOpenButton);
+// Debug: Add money button (bottom left)
+var addMoneyButton = LK.getAsset('buy_button', {
+	anchorX: 0.5,
+	anchorY: 0.5
+});
+addMoneyButton.x = 200;
+addMoneyButton.y = 2732 - 150;
+addMoneyButton.down = function () {
+	gameState.money += 50000;
+	updateUI();
+};
+game.addChild(addMoneyButton);
 game.addChild(tooltip);
 /**** 
-* MULTI-PURCHASABLE & OTHER UPGRADES
+* UPGRADE SYSTEM
 ****/ 
-var clusterUpgradeBaseCost = 1000;
-// We store an object for each upgrade. For multi-purchase upgrades (like coal_expert),
-// we allow repeated buys that keep doubling the cost, keep increasing effect, etc.
-var upgrades = [{
+// We split upgrades by category for our new sub-menu system
+var coalUpgrades = [{
 	id: 'coal_expert',
 	name: "Coal Expertise",
 	cost: 100,
 	multi: true,
-	// can be purchased repeatedly
 	level: 0,
-	// track how many times purchased
 	effect: "Doubles coal value each purchase",
-	tier: 1,
-	requires: null,
 	action: function action() {
 		this.level++;
-		// Each purchase x2 for coal
 		gameState.oreMultipliers.coal *= 2;
-		// Double cost for next time
 		this.cost *= 2;
 	}
-}, {
+}];
+var ironUpgrades = [{
 	id: 'unlock_iron',
 	name: "Unlock Iron Mining",
 	cost: 500,
 	effect: "Allows iron ore clusters to spawn",
-	tier: 2,
-	requires: null,
 	purchased: false,
 	action: function action() {
-		gameState.currentTier = 2;
+		gameState.currentTier = Math.max(gameState.currentTier, 2);
+		// Immediately spawn iron clusters
+		for (var i = 0; i < gameState.maxClustersPerType; i++) {
+			maybeSpawnCluster('iron');
+		}
 	}
 }, {
 	id: 'iron_expert',
 	name: "Iron Expertise",
 	cost: 2000,
-	effect: "Triple iron value (one-time)",
-	tier: 2,
+	effect: "Triple iron value",
 	requires: 'unlock_iron',
+	purchased: false,
 	action: function action() {
 		gameState.oreMultipliers.iron *= 3;
 	}
-}, {
+}];
+var goldUpgrades = [{
 	id: 'unlock_gold',
 	name: "Unlock Gold Mining",
 	cost: 5000,
 	effect: "Allows gold ore clusters to spawn",
-	tier: 3,
-	requires: null,
 	action: function action() {
-		gameState.currentTier = 3;
+		gameState.currentTier = Math.max(gameState.currentTier, 3);
+		// Immediately spawn gold
+		for (var i = 0; i < gameState.maxClustersPerType; i++) {
+			maybeSpawnCluster('gold');
+		}
 	}
 }, {
 	id: 'gold_expert',
 	name: "Gold Expertise",
 	cost: 10000,
-	effect: "Quadruple gold value (one-time)",
-	tier: 3,
+	effect: "Quadruple gold value",
 	requires: 'unlock_gold',
 	action: function action() {
 		gameState.oreMultipliers.gold *= 4;
 	}
-}, {
+}];
+var diamondUpgrades = [{
 	id: 'unlock_diamond',
 	name: "Unlock Diamond Mining",
 	cost: 20000,
 	effect: "Allows diamond ore clusters to spawn",
-	tier: 4,
-	requires: null,
 	action: function action() {
-		gameState.currentTier = 4;
+		gameState.currentTier = Math.max(gameState.currentTier, 4);
+		// Immediately spawn diamond
+		for (var i = 0; i < gameState.maxClustersPerType; i++) {
+			maybeSpawnCluster('diamond');
+		}
 	}
-}, {
+}];
+var generalUpgrades = [{
 	id: 'faster_respawn',
 	name: "Quicker Respawn",
 	cost: 8000,
-	effect: "Halves respawn time (min 500ms)",
-	tier: 2,
-	requires: null,
+	effect: "Halves respawn time (min 500 ms)",
 	action: function action() {
 		gameState.respawnTime = Math.max(500, gameState.respawnTime / 2);
 	}
 }, {
 	id: 'cluster_up',
-	name: "Cluster Growth [Tier 1]",
-	cost: clusterUpgradeBaseCost,
-	effect: "Increases cluster size range",
-	tier: 1,
-	requires: null,
+	name: "Cluster Growth",
+	cost: 1000,
+	effect: "Increase cluster size range",
+	purchased: false,
 	action: function action() {
 		if (gameState.clusterUpgradeTier < gameState.clusterConfigLevels.length - 1) {
 			gameState.clusterUpgradeTier++;
 		}
-		// Increase cost for next purchase
 		this.cost += 2000;
 	}
 }];
-var upgradeItemRefs = []; // store references so we can update them each frame
-function createUpgradeMenu() {
+// We can define a quick "requires" check function
+function meetsRequirement(upgList, upg) {
+	if (!upg.requires) {
+		return true;
+	}
+	// if upg requires 'xxx', find that upgrade in the same category
+	var needed = upgList.find(function (u) {
+		return u.id === upg.requires;
+	});
+	return needed && needed.purchased;
+}
+/**** 
+* MAIN MENU: 5 categories
+****/ 
+function createMainUpgradeMenu() {
 	upgradeMenu.removeChildren();
-	upgradeItemRefs = [];
-	// Background
+	// Big background
 	var menuBg = LK.getAsset('rectangle', {
-		width: 1600,
-		height: 1800,
+		width: 1800,
+		height: 2000,
 		color: 0x2a2a2a,
 		anchorX: 0.5,
 		anchorY: 0.5
 	});
 	menuBg.x = 2048 / 2;
-	menuBg.y = 2732 / 2;
+	// shift down slightly
+	menuBg.y = 2732 / 2 + 50;
 	upgradeMenu.addChild(menuBg);
-	// Update cluster upgrade display
-	var clusterUpObj = upgrades.find(function (u) {
-		return u.id === 'cluster_up';
-	});
-	if (clusterUpObj) {
-		clusterUpObj.name = "Cluster Growth [Tier " + (gameState.clusterUpgradeTier + 1) + "]";
-		var cfg = gameState.clusterConfig;
-		clusterUpObj.effect = "Spawns " + cfg.min + "-" + cfg.max + " per cluster";
-	}
-	// Build each upgrade row
-	upgrades.forEach(function (upg, i) {
-		var requirement = null;
-		if (upg.requires) {
-			requirement = upgrades.find(function (u) {
-				return u.id === upg.requires;
-			});
+	// We'll create 5 buttons for categories: Coal, Iron, Gold, Diamond, General
+	var categories = [{
+		name: "Coal Upgrades",
+		yOff: -600,
+		onClick: function onClick() {
+			createSubUpgradeMenu("Coal Upgrades", coalUpgrades);
 		}
-		var yPos = 2732 / 2 - 500 + i * 200;
-		// A container for the button + text
-		var itemContainer = new Container();
-		itemContainer.x = 0;
-		itemContainer.y = 0;
-		upgradeMenu.addChild(itemContainer);
-		// Button
+	}, {
+		name: "Iron Upgrades",
+		yOff: -300,
+		onClick: function onClick() {
+			createSubUpgradeMenu("Iron Upgrades", ironUpgrades);
+		}
+	}, {
+		name: "Gold Upgrades",
+		yOff: 0,
+		onClick: function onClick() {
+			createSubUpgradeMenu("Gold Upgrades", goldUpgrades);
+		}
+	}, {
+		name: "Diamond Upgrades",
+		yOff: 300,
+		onClick: function onClick() {
+			createSubUpgradeMenu("Diamond Upgrades", diamondUpgrades);
+		}
+	}, {
+		name: "General Upgrades",
+		yOff: 600,
+		onClick: function onClick() {
+			createSubUpgradeMenu("General Upgrades", generalUpgrades);
+		}
+	}];
+	var centerX = menuBg.x;
+	var centerY = menuBg.y;
+	categories.forEach(function (cat) {
 		var btn = LK.getAsset('buy_button', {
 			anchorX: 0.5,
 			anchorY: 0.5
 		});
-		btn.x = 2048 / 2;
-		btn.y = yPos;
-		itemContainer.addChild(btn);
-		// For multi levels, e.g. coal_expert, show the level in the name
+		btn.x = centerX;
+		btn.y = centerY + cat.yOff;
+		btn.down = cat.onClick;
+		upgradeMenu.addChild(btn);
+		var txt = new Text2(cat.name, {
+			size: 50,
+			fill: 0xFFFFFF,
+			align: 'center'
+		});
+		txt.anchor.set(0.5);
+		txt.x = btn.x;
+		txt.y = btn.y;
+		upgradeMenu.addChild(txt);
+	});
+	// Close button
+	var closeBtn = LK.getAsset('cancelButton', {
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	closeBtn.x = menuBg.x + 700;
+	closeBtn.y = menuBg.y - 800;
+	closeBtn.down = function () {
+		game.removeChild(upgradeMenu);
+	};
+	upgradeMenu.addChild(closeBtn);
+}
+/**** 
+* SUB MENU for a given category of upgrades
+****/ 
+var subUpgradeItemRefs = []; // track references to update color in real-time
+function createSubUpgradeMenu(title, upgList) {
+	upgradeMenu.removeChildren();
+	subUpgradeItemRefs = [];
+	// Big background
+	var menuBg = LK.getAsset('rectangle', {
+		width: 1800,
+		height: 2000,
+		color: 0x2a2a2a,
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	menuBg.x = 2048 / 2;
+	menuBg.y = 2732 / 2 + 50;
+	upgradeMenu.addChild(menuBg);
+	// Title
+	var titleText = new Text2(title, {
+		size: 60,
+		fill: 0xFFFFFF,
+		align: 'center'
+	});
+	titleText.anchor.set(0.5);
+	titleText.x = menuBg.x;
+	titleText.y = menuBg.y - 850;
+	upgradeMenu.addChild(titleText);
+	// Layout the upgrades in a single column
+	// We'll do ~150px vertical spacing between items
+	var startY = menuBg.y - 650;
+	upgList.forEach(function (upg, i) {
+		// Container for button + text
+		var c = new Container();
+		upgradeMenu.addChild(c);
+		var btn = LK.getAsset('buy_button', {
+			anchorX: 0.5,
+			anchorY: 0.5
+		});
+		btn.x = menuBg.x;
+		btn.y = startY + i * 150;
+		c.addChild(btn);
+		// Display name
 		var displayName = upg.name;
-		if (upg.id === 'coal_expert' && upg.level > 0) {
+		if (upg.level && upg.level > 0) {
 			displayName += " (Lv " + upg.level + ")";
 		}
 		var txtStr = displayName + "\n" + upg.effect + "\n$" + upg.cost;
 		var txt = new Text2(txtStr, {
 			size: 40,
-			align: 'center',
-			fill: 0x666666
+			fill: 0x666666,
+			align: 'center'
 		});
 		txt.anchor.set(0.5);
 		txt.x = btn.x;
 		txt.y = btn.y;
-		itemContainer.addChild(txt);
-		// On click
+		c.addChild(txt);
 		btn.down = function () {
-			var canBuy = checkUpgradeable(upg, requirement);
+			var canBuy = checkSubUpgradeBuyable(upgList, upg);
 			if (canBuy) {
 				gameState.money -= upg.cost;
-				// If single-purchase (no multi)
-				if (!upg.multi) {
-					upg.purchased = true;
-				}
-				// Perform upgrade
+				upg.purchased = true; // Mark purchased
 				upg.action();
-				// Refresh menu + UI
-				createUpgradeMenu();
 				updateUI();
+				// Refresh sub-menu so cost, text, etc. updates
+				createSubUpgradeMenu(title, upgList);
 			}
 		};
-		// Keep references for real-time color update
-		upgradeItemRefs.push({
+		subUpgradeItemRefs.push({
 			upgrade: upg,
-			requirement: requirement,
+			upgradesList: upgList,
 			textObj: txt
 		});
 	});
-	// Close button
-	var closeBtn = LK.getAsset('cancelButton', {
+	// Back button
+	var backBtn = LK.getAsset('cancelButton', {
 		anchorX: 0.5,
 		anchorY: 0.5
 	});
-	closeBtn.x = 2048 / 2 + 600;
-	closeBtn.y = 2732 / 2 - 700;
-	closeBtn.down = function () {
-		game.removeChild(upgradeMenu);
+	backBtn.x = menuBg.x + 700;
+	backBtn.y = menuBg.y - 800;
+	backBtn.down = function () {
+		createMainUpgradeMenu();
 	};
-	upgradeMenu.addChild(closeBtn);
+	upgradeMenu.addChild(backBtn);
 }
-function checkUpgradeable(upg, requirement) {
-	var hasReq = true;
-	if (requirement && !requirement.purchased) {
-		hasReq = false;
+// Helper to see if we can buy an upgrade in a sub-menu
+function checkSubUpgradeBuyable(upgList, upg) {
+	// If we have a "requires" that isn't purchased, can't buy
+	if (!meetsRequirement(upgList, upg)) {
+		return false;
 	}
-	// If multi = true, do not block purchase after first time
+	// If it's multi: we do not block further purchases. 
+	// If not multi & purchased => no
 	if (!upg.multi && upg.purchased) {
 		return false;
 	}
-	// Must have enough money
 	if (gameState.money < upg.cost) {
 		return false;
 	}
-	return hasReq;
+	return true;
 }
+// Also re-check color each frame
 /**** 
-* UPDATE UI
+* MAIN GAME LOOP: updating the buy menu text colors
 ****/ 
-function updateUI() {
-	moneyDisplay.setText("$" + gameState.money.toLocaleString() + "\n" + "Multipliers: C" + gameState.oreMultipliers.coal + "x " + "I" + gameState.oreMultipliers.iron + "x " + "G" + gameState.oreMultipliers.gold + "x " + "D" + gameState.oreMultipliers.diamond + "x");
-	moneyDisplay.x = 2048 / 2 - moneyDisplay.width / 2;
-}
-/**** 
-* MAIN GAME UPDATE
-****/ 
 game.update = function () {
 	// 1) Miner logic
 	miner.update();
-	// 2) For each cluster, update each ore's health bar & alpha
+	// 2) Update ore visuals
 	clusters.forEach(function (cluster) {
 		cluster.oreList.forEach(function (ore) {
 			if (ore.health > 0) {
 				var fraction = ore.health / ore.maxHealth;
 				ore.healthBar.width = 120 * fraction;
 				ore.healthBar.fill = interpolateColor(0xFF0000, 0x00FF00, fraction);
-				ore.alpha = fraction; // fade
+				ore.alpha = fraction;
 			}
 		});
 	});
-	// 3) If the upgradeMenu is open, check if items became purchasable
+	// 3) If a sub-menu is open, re-check color
 	if (upgradeMenu.parent) {
-		upgradeItemRefs.forEach(function (ref) {
-			var canBuy = checkUpgradeable(ref.upgrade, ref.requirement);
-			// If canBuy => text color = 0xFFFFFF, else 0x666666
+		subUpgradeItemRefs.forEach(function (ref) {
+			var upg = ref.upgrade;
+			var canBuy = checkSubUpgradeBuyable(ref.upgradesList, upg);
 			if (ref.textObj && ref.textObj.style) {
-				if (canBuy) {
-					ref.textObj.style.fill = 0xFFFFFF;
-				} else {
-					ref.textObj.style.fill = 0x666666;
-				}
+				ref.textObj.style.fill = canBuy ? 0xFFFFFF : 0x666666;
 			}
 		});
 	}
 };
 /**** 
+* UI UPDATE
+****/ 
+function updateUI() {
+	moneyDisplay.setText("$" + gameState.money.toLocaleString() + "\n" + "Multipliers: " + "C" + gameState.oreMultipliers.coal + "x " + "I" + gameState.oreMultipliers.iron + "x " + "G" + gameState.oreMultipliers.gold + "x " + "D" + gameState.oreMultipliers.diamond + "x");
+	moneyDisplay.x = 2048 / 2 - moneyDisplay.width / 2;
+}
+/**** 
 * SAVE & LOAD
 ****/ 
 LK.saveGame = function () {
 	return gameState;
@@ -636,17 +697,16 @@
 	gameState = data;
 	updateUI();
 };
 /**** 
-* INITIAL SETUP
-* Spawn some clusters for each type up to currentTier
+* INITIAL SPAWN
+* Spawn up to maxClusters for each ore up to currentTier
 ****/ 
 function initialSpawn() {
 	var oreTypes = ['coal', 'iron', 'gold', 'diamond'];
 	oreTypes.forEach(function (type, idx) {
 		var tier = idx + 1;
 		if (tier <= gameState.currentTier) {
-			// spawn up to maxClustersPerType immediately
 			for (var i = 0; i < gameState.maxClustersPerType; i++) {
 				maybeSpawnCluster(type);
 			}
 		}