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.