Hi Alina, as mamta said above, yes u definetely need a visiting\transit visa if you do want to come out of the airport and visit the city. If you are holding a Nepali passport, then there is probability of visa being rejected most of the time and with out a proper visa the Hong Kong Imigration department wont let you out. If you got a visa ready and still want to visit the cities of Hong Kong, from the airport you can take a direct Hong Kong express train which will lead to the major cites of HongKong within half an hour at a cost of HKD$100= USD$13. You can check out places like Central, Wanchai, TsimTshaTshui and peaks with a 13 hours transit time depending upon your arrival time at HongKong  and make it back at airport in time. It will be more convience if you got someone to take care of you around like your friends or family so that you can manage your time easily. But if you want to stay inside the airport, yes there are lots of good restaurants and shopping arcades inside the airport though fairly expensive then the cities. You can experience 4D Cinema too but the last show time is around 9:00pm HK local time. You can chat or surf sajha and eat some burger of burger kings inside there for 13 hours . If you do need any more information do let know. Cheers. Nav