“RetroArch is coming to Steam as a free download on July 30, marking what appears to be the largest non-commercial emulation launch ever on Valve’s digital download storefront. The news came on Friday via an announcement from Libretro, the open source development collective that maintains the RetroArch launcher app for a massive range of operating systems.”

Source.

It will be coming to Steam on July 30, it will be identical to the one you could download on the RetroArch’s official site, the team is limiting the Steam’s launch to windows to make sure they can handle the demand before adding MacOS and Linux options. The app will direct you to emulator download options with a few clicks through its default online connected interface, RetroArch does not include download links within the app to console-specific BIOS files. For most emulators you will need one of these to boots any softwares, if you don’t rip a BIOS file direclty form your owned console, you may enter a gray area. The same happens for whatever games or ROMs you load.