I already own a physical copy of Oblivion GOTY and it is installed and modded as well. I am considering purchasing the quakecon pack from steam and bundled with that is the Oblivion Deluxe version.

What happens when I have two different version of Oblivion like that? If I install it through steam will it act like a completely separate game, or does it merge into my already existing game?

Please share your wisdom, thank you.

To my knowledge, a game won't download on Steam if you already own it. Either that, or if it does, it probably merges in, but I'm speaking from limited experience.

You will have two versions of it.. Steam games are usually installed in the steam directory.

It'll be two different versions, Steam games have their own directory.

It'll act like a completely separate game, with it's own saves and everything likely. Although you can just move your current saves into the steam directory folder for Oblivion and they ought to work without a hitch. You can also install all of your mods to the steam Oblivion, and they will work.

When you install Oblivion from the disc, its usual install directory is C:\Program Files\Bethesda Softworks\Oblivion. When you install Oblivion through Steam, it acts like a separate game, like the above posts mentioned. The average installation directory for that is C:\Program Files\Steam\SteamApps\Common\Oblivion.

From that point on, the layout is exactly like the disc version. So if you want to install mods, they still go in that Oblivion folder, you still move meshes to the meshes folder, textures to the textures folder, activate mods through the launcher, etc.

What you'll have to do differently is remember to specify that directory as your Oblivion installation. Things like the Construction Set, OBMM, OBSE, etc, will need to be installed to there, not in the expected folder.

And this general rule applies for just about all Steam games. When you install games through Steam, they take the same form (usually) as their physical media counterparts with the biggest difference being a relocation to the one Steam folder. The other big difference is that Steam .exe's are usually different than the usual ones, because they are programmed to launch through Steam and not a disc. They pretty much work the same, but some third-party programs might not like one or the other, depending on which it was programmed around.

it may end up using the same directory for configurations and saves, since oblivion uses "My Documents" for those

Thank you very much for the reply everyone. Depending on what the sale looks like on sunday I'll probably get that quakecon pack now.