Molokai is a Vim port of the monokai theme for TextMate originally created by Wimer Hazenberg.
By default, it has a dark gray background based on the version created by Hamish Stuart Macpherson for the E editor.
256-Color terminals are also supported, though there are some differences with the Gui version. Only the dark gray background style is supported on terminal vim at this time.
Use a plugin manager, i.e:
or copy the file on your .vim/colors folder.