How to make playable discs for steam games (not backup install disks)

You should be able to create a Steam library folder on the disc like you would on a regular hard drive. You'll need Steam installed on the computer you're running the game on and you may need to add the library in Steam's download options every time it's inserted, manually, but it should be able to run the games.

See here for managing Steam library folders.

The problem is some games check with Steam that the currently signed in user has bought the game. DRM biting you in the backside.

I would not recommend moving a library folder onto a disk. Some games were meant to be played on disks and some are not. The problem is you typically can only write once to a disk. If a game constantly changes files, you may have very unexpected results. A solution would be to use USB drives, but that is also not recommended.

So I've tried this over a year ago with some games. My answer it's totally possible to run games straight from a DVD but it has some issues, first, you need a game that is very light that doesn't rely on data streaming from the HDD, second the game can't have config or save games on the install directory, and thirdly, the game needs to be DRM-Free. The best game to play off a DVD for some reason is Amnesia: The Dark Descent, you can get the game DRM free on GOG and does all the above. It works really well, but the problem and redundant issue are that there's no reason to play games off a DVD. Windows for some reason loves to store data in Temporary files to ease up load times if Windows knows you're actively loading shit. So by the time Windows is reading off the disc, it's just gonna store on your HDD temporary and you'll start to notice load times are 200% faster.