/**** 
* Plugins
****/ 
var tween = LK.import("@upit/tween.v1");

/**** 
* Classes
****/ 
var Block = Container.expand(function (blockType) {
	var self = Container.call(this);
	this.blockType = blockType;
	this.gridX = 0;
	this.gridY = 0;
	var blockGraphics = self.attachAsset(blockType, {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Add slight border effect
	blockGraphics.alpha = 0.9;
	self.setGridPosition = function (gridX, gridY) {
		self.gridX = gridX;
		self.gridY = gridY;
		self.x = gridX * 80 + 40;
		self.y = gridY * 80 + 40;
	};
	return self;
});
var GridHighlight = Container.expand(function () {
	var self = Container.call(this);
	var highlightGraphics = self.attachAsset('highlight', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	highlightGraphics.alpha = 0.3;
	self.visible = false;
	self.showAt = function (gridX, gridY) {
		self.x = gridX * 80 + 40;
		self.y = gridY * 80 + 40;
		self.visible = true;
	};
	self.hide = function () {
		self.visible = false;
	};
	return self;
});
var InventorySlot = Container.expand(function (blockType, index) {
	var self = Container.call(this);
	this.blockType = blockType;
	this.count = 10; // Start with 10 of each block type
	var slotBackground = self.attachAsset('inventorySlot', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	var blockPreview = self.attachAsset(blockType, {
		anchorX: 0.5,
		anchorY: 0.5,
		scaleX: 0.8,
		scaleY: 0.8
	});
	var countText = new Text2(self.count.toString(), {
		size: 24,
		fill: 0xFFFFFF
	});
	countText.anchor.set(0.5, 0.5);
	countText.x = 30;
	countText.y = 30;
	self.addChild(countText);
	self.x = 150 + index * 120;
	self.y = 2600;
	self.updateCount = function (newCount) {
		self.count = Math.max(0, newCount);
		countText.setText(self.count.toString());
	};
	self.down = function (x, y, obj) {
		if (self.count > 0) {
			selectedBlockType = self.blockType;
			updateSelectedIndicator();
		}
	};
	return self;
});
var ModeButton = Container.expand(function () {
	var self = Container.call(this);
	var buttonBackground = self.attachAsset('uiButton', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	var buttonText = new Text2('BUILD', {
		size: 36,
		fill: 0xFFFFFF
	});
	buttonText.anchor.set(0.5, 0.5);
	self.addChild(buttonText);
	self.x = 1024;
	self.y = 2500;
	self.updateMode = function (isBuildMode) {
		if (isBuildMode) {
			buttonText.setText('BUILD');
			buttonBackground.tint = 0x00AA00;
		} else {
			buttonText.setText('BREAK');
			buttonBackground.tint = 0xAA0000;
		}
	};
	self.down = function (x, y, obj) {
		isBuildMode = !isBuildMode;
		self.updateMode(isBuildMode);
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x87CEEB
});

/**** 
* Game Code
****/ 
// Sound effects
// UI elements
// Grid-based building blocks
// Game state variables
var gameGrid = {};
var gridWidth = 25;
var gridHeight = 30;
var isBuildMode = true;
var selectedBlockType = 'stone';
// UI elements
var gridHighlight;
var inventorySlots = [];
var modeButton;
var selectedIndicator;
// Initialize grid highlight
gridHighlight = game.addChild(new GridHighlight());
// Initialize inventory
var blockTypes = ['stone', 'wood', 'dirt', 'grass'];
for (var i = 0; i < blockTypes.length; i++) {
	var slot = new InventorySlot(blockTypes[i], i);
	inventorySlots.push(slot);
	game.addChild(slot);
}
// Initialize mode button
modeButton = game.addChild(new ModeButton());
modeButton.updateMode(isBuildMode);
// Selected block indicator
selectedIndicator = LK.getAsset('highlight', {
	anchorX: 0.5,
	anchorY: 0.5,
	scaleX: 1.2,
	scaleY: 1.2
});
selectedIndicator.alpha = 0.5;
game.addChild(selectedIndicator);
function updateSelectedIndicator() {
	for (var i = 0; i < inventorySlots.length; i++) {
		if (inventorySlots[i].blockType === selectedBlockType) {
			selectedIndicator.x = inventorySlots[i].x;
			selectedIndicator.y = inventorySlots[i].y;
			break;
		}
	}
}
updateSelectedIndicator();
function worldToGrid(worldX, worldY) {
	return {
		x: Math.floor(worldX / 80),
		y: Math.floor(worldY / 80)
	};
}
function isValidGridPosition(gridX, gridY) {
	return gridX >= 0 && gridX < gridWidth && gridY >= 0 && gridY < gridHeight;
}
function getGridKey(gridX, gridY) {
	return gridX + ',' + gridY;
}
function hasBlockAt(gridX, gridY) {
	return gameGrid[getGridKey(gridX, gridY)] !== undefined;
}
function getInventorySlot(blockType) {
	for (var i = 0; i < inventorySlots.length; i++) {
		if (inventorySlots[i].blockType === blockType) {
			return inventorySlots[i];
		}
	}
	return null;
}
function placeBlock(gridX, gridY, blockType) {
	if (!isValidGridPosition(gridX, gridY) || hasBlockAt(gridX, gridY)) {
		return false;
	}
	var slot = getInventorySlot(blockType);
	if (!slot || slot.count <= 0) {
		return false;
	}
	var block = new Block(blockType);
	block.setGridPosition(gridX, gridY);
	game.addChild(block);
	gameGrid[getGridKey(gridX, gridY)] = block;
	slot.updateCount(slot.count - 1);
	LK.getSound('place').play();
	// Place animation
	block.alpha = 0;
	tween(block, {
		alpha: 1
	}, {
		duration: 200
	});
	return true;
}
function breakBlock(gridX, gridY) {
	var gridKey = getGridKey(gridX, gridY);
	var block = gameGrid[gridKey];
	if (!block) {
		return false;
	}
	var slot = getInventorySlot(block.blockType);
	if (slot) {
		slot.updateCount(slot.count + 1);
	}
	LK.getSound('break').play();
	// Break animation
	tween(block, {
		alpha: 0,
		scaleX: 0.5,
		scaleY: 0.5
	}, {
		duration: 200,
		onFinish: function onFinish() {
			block.destroy();
		}
	});
	delete gameGrid[gridKey];
	return true;
}
var lastHoverGridX = -1;
var lastHoverGridY = -1;
game.move = function (x, y, obj) {
	// Only show highlight in build area
	if (y < 2400) {
		var gridPos = worldToGrid(x, y);
		if (isValidGridPosition(gridPos.x, gridPos.y)) {
			if (gridPos.x !== lastHoverGridX || gridPos.y !== lastHoverGridY) {
				if (isBuildMode && !hasBlockAt(gridPos.x, gridPos.y)) {
					gridHighlight.showAt(gridPos.x, gridPos.y);
				} else if (!isBuildMode && hasBlockAt(gridPos.x, gridPos.y)) {
					gridHighlight.showAt(gridPos.x, gridPos.y);
				} else {
					gridHighlight.hide();
				}
				lastHoverGridX = gridPos.x;
				lastHoverGridY = gridPos.y;
			}
		} else {
			gridHighlight.hide();
			lastHoverGridX = -1;
			lastHoverGridY = -1;
		}
	} else {
		gridHighlight.hide();
		lastHoverGridX = -1;
		lastHoverGridY = -1;
	}
};
game.down = function (x, y, obj) {
	// Only allow building/breaking in the main game area
	if (y < 2400) {
		var gridPos = worldToGrid(x, y);
		if (isValidGridPosition(gridPos.x, gridPos.y)) {
			if (isBuildMode) {
				placeBlock(gridPos.x, gridPos.y, selectedBlockType);
			} else {
				breakBlock(gridPos.x, gridPos.y);
			}
		}
	}
};
game.update = function () {
	// Update game state if needed
};

===================================================================
--- original.js
+++ change.js
@@ -135,9 +135,9 @@
 var selectedIndicator;
 // Initialize grid highlight
 gridHighlight = game.addChild(new GridHighlight());
 // Initialize inventory
-var blockTypes = ['stone', 'wood', 'dirt'];
+var blockTypes = ['stone', 'wood', 'dirt', 'grass'];
 for (var i = 0; i < blockTypes.length; i++) {
 	var slot = new InventorySlot(blockTypes[i], i);
 	inventorySlots.push(slot);
 	game.addChild(slot);