I had oblivion on a disc for a long time. I recently moved and lost the disc. So I decided I'd buy it on steam so I never have this problem again.
Well now I'm on really poor internet, and am looking at a 20 hour download at best for this. I already have MOST of the game (the GOTY edition) installed on my hard drive already. Would it be possible to copy/paste some of the files from my other installation into the steam installation, removing the need for a lot of the download?
Best Answer
I've not tried it with oblivion, but I have moved games from one steam install to another this way. It should work similarly, but will probably still have to download a few files, mostly the ones that are steamworks encrypted.
1) start the steam download and pause it once it has begun downloading anything. This will create the directory for the game.
2) close steam
3) Copy the disc installed folder into the steam install. This will be something like /Steam/steamapps/common/oblivion/
4) Inside the steam directory is a ClientRegistry.blob file. This tells steam what games and files you have installed. Delete it (or move it to a different location if you prefer, but steam will recreate it on login).
5) Restart steam. It will verify the files it has, and hopefully most of the art files are the same from the disc version to the steam version.
6) After it's done downloading, right click on oblivion, go into properties and select the local files tab. Press the "Verify Integrity of Game Cache" button. This will force steam to checksum the files and download any that don't match exactly.
I'm not sure how much downloading it will save you, but I would expect the art files and the majority of the resource files won't need downloaded.