mining, coal, resource, Stardew Valley, underground, caves, rocks, pickaxe, mine levels, dust sprites, cart, black, lumps, geodes, farm, video game environment, torch light, spelunking, ore nodes, coal bin, backpack, pixel art, side view, ambient lighting, game HUD, resource gathering, inventory management, virtual world, coal mining, in-game economy, crafting material, furnace fuel, midday, soft shadows, vibrant colors, 2D game graphics, exploration, resource collection.