i have 2 ideas 1 is that you make a raspberry pi 3 (or raspberry pi zero) retro emulation console my requierments are that it has: 2 anlog joy sticks,2 shoulder buttons,a way to conect with freinds (for games like pokemon or tetris),it runs emulation station (games console i would conseter gamecube,n64,ps2,ps1,nes,snes,neogeo pocket,turbo grafix,sega genises,sega megadrive,gameboy,gameboy color,gameboy advaced),at least 2 usb ports and rechargable battery,it has a screen,4 action buttons,1 dpad.most of these can be perchased from adafruit.com or amazon or salvaged from other things.my second idea is u make a portable raspberry pi gamin pc all buttons same as the first so have fun if u like my idea.