I have no experience with captioning, but we are developing a game and we want to make it as accessible as possible so we thought of 2 levels of subtitles: dialogues and Closed Captions (dialogues + sound effects).
The problem I can think of is what sounds need to be transcripted in Closed Captions? All sounds of the game could clutter the screen with subtitles and distract the player. Too few sounds and the player could miss some details.
For example we could have an electric door which makes some sound when opened or closed, this kind of sound should be transcripted always? Or just the first time it's encountered, and then the user will know that all the similar doors should make the same sound? And is it too much to put 2 subtitles (one for opening, one for closing)?