Lots of good useful help here on how to get Oblivion running, and I'm getting there now. Still got sound problems, but I have got mods running. People are asking about the file locations and so here are some tips from me in the hope that it will save you some of the hours I spent on wild goose chases around the filesystem...
NB: I have a Cider version of the Oblivion GOTY edition, which as standard, ran with a black screen and no plugins.
Priority 1 = fix the black screen
In the game, go to options and turn off HDR
Priority 2 = Activate the DLC plugins
For this and the next steps, the thing to realise is that your plug ins, Oblivion.ini and Plugins.txt files are in different places!
To find your plug ins, control select the Oblivion icon in Applications and Show Contents. This will reveal the hidden file structure within. Navigate through the folders to Resources>transgaming>c_drive>Bethesda Softworks>Oblivion. You can make an alias to this folder for easier navigation next time.
Within the Oblivion folder site the game and it's Data folder. It's in Data that plugins go. You'll need to look in here and get the file names of any DLC addons, so keep this window open.
Now for the Plugins.txt file. This will tell Oblivion what to load and in what order.
Look in yourHomeFolder>Library>Preferences>Oblivion Preferences>p_drive>User>Local Settings>Application Data>Oblivion
You will likely have to create the Plugins.txt file from scratch. I used BBEdit and found it important to set DOS line breaks. A basic file will look like this...
# This file is used to tell Oblivion which data files to load.
# Use the "data files" option in the Oblivion launcher to choose which files
# you want. Please do not modify this file.
I read that oblivion.esm goes first always and in the DLC list, Knights goes last. It works for me so far.
Priority 3 = Fiddle in the Oblivion.ini file with tweaks I read about in forums
Look in yourHomeFolder>Library>Preferences>Oblivion Preferences>p_drive>User>Local Settings>My Documents>My Games>Oblivion
This is the location of the Oblivion.ini that seems to make a difference. There are others in the main application folder, but these don't seem to do anything (for me).
This is the file to 'experiment with' to try and fix the sound bug. I haven't had any luck yet.
Priority 4 = Add some other plug ins, such as Unofficial Oblivion Patch.esp
Remember that plug ins will live in the Data folder where the app is. You can download them from sites, and might need a .7z unzipper, but once you have it it's worth being aware that you'll have to manual install any files. This is fiddly and needs to be done with care to match up the correct folders, etc. and not to delete anything unintentionally.
Having added files carefully, you'll also have a .esp file in the Data folder too. Go and add its name onto the end of your Plugins.txt file and save it.
That should see your plug in load next time you run Oblivion and enter the game world.
So, I'm up and running and on my way to see Jauffre. If I sort the sound bug, or find any other great revelations, I'll post somewhere on the board.
Good luck! ... and thanks again to the posters above who helped me get everything up and running.
Thanks for the post it helped sort of. Here is my problem I did everything that you said to do and now Oblivion wont work at all. Am I doing something wrong?
Here is what my plugins text document looks like.
#This file is used to tell Oblivion which data files to load.
#Use the "data files" option in the Oblivion launcher to choose which files
#you want. Please do not modify this file.
Open Cities Full.esp
Open Cities Full + Bravil Blood&Mud.esp
Unofficial Oblivion Patch.esp
Unofficial Shivering Isles Patch.esp
The Lost Spires.esp
What could I be doing wrong should I delete and reinstall?