select city then show homepage

I was looking for a functionality, If it is possible to have in wordpress theme. Or if there’s a plugin to have this kind of functionality set in theme.
Please See this Website. www.lootlo.pk When you first visite this website it will ask you to select a city, then it will show the Deals with respect to the City you select.
The Same kind of functionality i want to set in our theme. Our current theme don’t have this functionality. Any help or advice would be Appreciated.