Pi Entertainment System is described as 'PES is a graphical front end for a variety of games console emulators that has been written in Python which is intended for use on the Raspberry Pi' and is an app in the OS & Utilities category. There are four alternatives to Pi Entertainment System for a variety of platforms, including Linux, Raspberry Pi, Odroid, Windows and Mac. The best alternative is Lakka, which is both free and Open Source. Other great apps like Pi Entertainment System are Retropie (Free, Open Source), Recalbox (Free, Open Source) and Batocera.linux (Free, Open Source).
RetroPie allows you to turn your Raspberry Pi or PC into a retro-gaming machine. It builds upon Raspbian, EmulationStation, RetroArch and many other projects to enable you to play your favourite classic games with the minimum set-up.
batocera.linux is an operating system (like Windows 10 and Mac OS) specialized in retrogaming available for your pc and different nano computers like the Raspberry and the Odroids. Note that you must own games you play in order to respect legality.