No modern AAA games have been released this way, but there is at least one game made specifically for libretro (Dinothawr) and a few other games that have been converted into "contentless" libretro cores (Cave Story, Mr. Boom, Rick Dangerous).

The games (or their engines/emulators) would have to be modified to use the libretro API for things like input, rendering, and sound. Though it doesn't look terribly hard to program for, it does tie the game to RetroArch (or another libretro frontend) and possibly limit what the program can do.

I thought I'd also bring up Lutris, which is not only a libretro frontend but also a frontend for numerous other game platforms. It may not have the game console-like UI of RetroArch, but I think if you must have all games under one launcher, it's the best you could hope for.