PC Game Shop

function pcGameShop(input) {
    let volume = Number(input[0]);
    let hearthstones = 0,
        fornites = 0,
        overwatches = 0,
        others = 0;

    for (let i = 1; i <= volume; i++) {
        let game = input[i];
        switch (game) {
            case "Hearthstone":
                hearthstones++;
                break;
            case "Fornite":
                fornites++;
                break;
            case "Overwatch":
                overwatches++;
                break;
            default:
                others++;
                break;
        }
    }

    console.log(`Hearthstone - ${(hearthstones / volume * 100).toFixed(2)}%`);
    console.log(`Fornite - ${(fornites / volume * 100).toFixed(2)}%`);
    console.log(`Overwatch - ${(overwatches / volume * 100).toFixed(2)}%`);
    console.log(`Others - ${(others / volume * 100).toFixed(2)}%`);
}

РЕШЕНИЕ С РЕЧНИК, ТЕРНАРЕН ОПЕРАТОР И FOR IN:

function pcGameShop(input) {
    let products = { 'Hearthstone': 0, 'Fornite': 0, 'Overwatch': 0, 'Others': 0 };
    let volume = Number(input[0]);

    for (let i = 1; i <= volume; i++) {
        let game = input[i];
        products[game in products ? game : 'Others']++;
    }

    for (let product in products) {
        console.log(`${product} - ${(products[product] / volume * 100).toFixed(2)}%`);
    }
}

И леко тарикатската:)

function pcGameShop(input) {
    let products = { 'Hearthstone': 0, 'Fornite': 0, 'Overwatch': 0, 'Others': 0 };

    for (let i = 1; i < input.length; i++) {
        products[input[i] in products ? input[i] : 'Others']++;
    }

    for (let product in products) {
        console.log(`${product} - ${(products[product] / Number(input[0]) * 100).toFixed(2)}%`);
    }
}