I took these categories (main and sub-categories) from an official page of Google and transformed them into a JSON file. The purpose was to use these categories in my Android Apps and Games Market website https://apkbucket.net. I'm putting this as a gist for public with an intention that this might help someone else too.

android-apps-games-categories-as-json.json

[
    {
        "name": "Apps",
        "children": [
            {
                "name": "Art & Design",
                "description": "Sketchbooks, painter tools, art & design tools, coloring books"
            },
            {
                "name": "Auto & Vehicles",
                "description": "Auto shopping, auto insurance, auto price comparison, road safety, auto reviews & news"
            },
            {
                "name": "Beauty",
                "description": "Makeup tutorials, makeover tools, hair styling, beauty shopping, makeup simulators"
            },
            {
                "name": "Books & Reference",
                "description": "Book readers, reference books, text books, dictionaries, thesaurus, wikis"
            },
            {
                "name": "Business",
                "description": "Document editor\/reader, package tracking, remote desktop, email management, job search"
            },
            {
                "name": "Comics",
                "description": "Comic players, comic titles"
            },
            {
                "name": "Communications",
                "description": "Messaging, chat\/IM, dialers, address books, browsers, call management"
            },
            {
                "name": "Dating",
                "description": "Matchmaking, courtship, relationship building, meeting new people, finding love"
            },
            {
                "name": "Education",
                "description": "Exam preparations, study-aids, vocabulary, educational games, language learning"
            },
            {
                "name": "Entertainment",
                "description": "Streaming video, Movies, TV, interactive entertainment"
            },
            {
                "name": "Events",
                "description": "Concert tickets, sporting event tickets, ticket resales, movie tickets"
            },
            {
                "name": "Finance",
                "description": "Banking, payment, ATM finders, financial news, insurance, taxes, portfolio\/trading, tip calculators"
            },
            {
                "name": "Food & Drink",
                "description": "Recipes, restaurants, food guides, wine tasting & discovery, beverage recipes"
            },
            {
                "name": "Health & Fitness",
                "description": "Personal fitness, workout tracking, diet and nutritional tips, health & safety, etc."
            },
            {
                "name": "House & Home",
                "description": "House & apartment search, home improvement, interior decoration, mortgages, real estate"
            },
            {
                "name": "Libraries & Demo",
                "description": "Software libraries, technical demos"
            },
            {
                "name": "Lifestyle",
                "description": "Style guides, wedding & party planning, how-to guides"
            },
            {
                "name": "Maps & Navigation",
                "description": "Navigation tools, GPS, mapping, transit tools, public transportation"
            },
            {
                "name": "Medical",
                "description": "Drug & clinical references, calculators, handbooks for health-care providers, medical journals & news"
            },
            {
                "name": "Music & Audio",
                "description": "Music services, radios, music players"
            },
            {
                "name": "News & Magazine",
                "description": "Newspapers, news aggregators, magazines, blogging"
            },
            {
                "name": "Parenting",
                "description": "Pregnancy, infant care & monitoring, childcare"
            },
            {
                "name": "Personalization",
                "description": "Wallpapers, live wallpapers, home screen, lock screen, ringtones"
            },
            {
                "name": "Photography",
                "description": "Cameras, photo editing tools, photo management and sharing"
            },
            {
                "name": "Productivity",
                "description": "Notepad, to do list, keyboard, printing, calendar, backup, calculator, conversion"
            },
            {
                "name": "Shopping",
                "description": "Online shopping, auctions, coupons, price comparison, grocery lists, product reviews"
            },
            {
                "name": "Social",
                "description": "Social networking, check-in"
            },
            {
                "name": "Sports",
                "description": "Sports news & commentary, score tracking, fantasy team management, game coverage"
            },
            {
                "name": "Tools",
                "description": "Tools for Android devices"
            },
            {
                "name": "Travel & Local",
                "description": "Trip booking tools, ride sharing, taxis, city guides, local business information, trip management tools, tour booking"
            },
            {
                "name": "Video Players & Editors",
                "description": "Video players, video editors, media storage"
            },
            {
                "name": "Weather",
                "description": "Weather reports"
            }
        ]
    },
    {
        "name": "Games",
        "children": [
            {
                "name": "Action",
                "description": "Action games"
            },
            {
                "name": "Adventure",
                "description": "Adventure games"
            },
            {
                "name": "Arcade",
                "description": "Arcade games"
            },
            {
                "name": "Board",
                "description": "Board games"
            },
            {
                "name": "Card",
                "description": "Card games"
            },
            {
                "name": "Casino",
                "description": "Casino games"
            },
            {
                "name": "Casual",
                "description": "Casual games"
            },
            {
                "name": "Educational",
                "description": "Educational games"
            },
            {
                "name": "Music",
                "description": "Music games"
            },
            {
                "name": "Puzzle",
                "description": "Puzzle games"
            },
            {
                "name": "Racing",
                "description": "Racing games"
            },
            {
                "name": "Role Playing",
                "description": "Role Playing games"
            },
            {
                "name": "Simulation",
                "description": "Simulation games"
            },
            {
                "name": "Sports",
                "description": "Sports games"
            },
            {
                "name": "Strategy",
                "description": "Strategy games"
            },
            {
                "name": "Trivia",
                "description": "Trivia games"
            },
            {
                "name": "Word",
                "description": "Word games"
            }
        ]
    }
]