This box right here, there are 15 gaming consoles in it. No emulators here, it is literally 15 different consoles. All powered by one power supply.
The creator spent 3,500 hours over 3 years to make this, laying out 300 meters of cabling inside what ended up being a 20kg (44lbs) box. It is currently unique, so you cant buy it. However with a little skill you can easily build one yourself.