Making a 2D 16-bit game.

I am trying to make a 2d 16-bit game. Like a Sega Genesis or SNES style game. the game will have the same color pallete as the console, the same sound type, same buttons, etc. But i am not able to figure out how to create/convert my pixel art into 16 bit. The art softwares i use are aseprite,gimp and krita.Any help will be greatly appreciated.