Is writing for games something that can be done by itself or does it generally something else like artist, music and sound etc.

Writing for games runs the gamut from one person sitting in a room with a brief from the design team right up to writers as part of the on-site development team.

An example of something in the middle might be thus:
An in-house writer or narrative designer prepares a framework and place-holder dialogue for any important scenes, which is then sent off to dedicated writer to flesh out and modify according to a brief from the design team.

Each evening or morning, the narrative designer is sent 'dailies' from the writer; they give feedback on anything that is not quite right yet. Meanwhile, the narrative designer makes sure that the art and sound assets match the story.

Finally, the writer submits their final draft, the narrative designer makes a few final tweaks, the producer signs off on it and everyone gets paid.

As you see, games writing does not really happen in isolation, but a games writer may work in relative isolation.

Quote: Original post by reaper567
Is writing for games something that can be done by itself or does it generally something else like artist, music and sound etc.

That last part of the question seems to be missing some words.
Here's two places where you can find information on writing for games:
http://www.sloperama.com/advice/lesson32.htm
http://www.igda.org/writing/

Thank you for the help, please excuse my grammar as I was in a hurry this morning. The question I really meant to ask was if writing the story was just a side job that the game designer might do or if you actually hire a separate person just for writing, but I think I have a good enough explanation now.

I have seen studios collar a designer to do the writing, I have even seen the lead scripter end up writing for the game, but it is not really a good idea.