This can be a good system for people who want to play their original media. But for anyone else, a $150 DE-10 Nano running MiSTer has excellent PCE, SGFx, and PCECD support.
Later you can also add a $30 32MB, or $60 128MB SDRAM module which will give you access to an FPGA NES, SNES, Genesis, SegaCD, NeoGeo, GB(C), GBA, SMS, GG, CPS (CPS1.5 is very close, with CPS2 following a little later). It can also run a bunch of computers including C64, Amiga, and a 486 DOS PC. As well as a ton of classic arcade games of which Gauntlet is a recently supported release.
https://github.com/MiSTer-devel/Main_MiSTer/wiki
It may look complex, but I've found it easier to set up and use than a RetroPi. It does allow you to go overboard and do things like lag-less RGB/Component output to a CRT TV and playing old lightgun games. But you can also map any controller to be usable on any system. And even use a Wiimote as a lightgun like on an emulator on a PC, except the backend is still the FPGA console.