Great news Celt! I’ll add some advice later re steam version
@CELTICEMPIRE
Okay..a few pieces of advice on the steam version:
1) You only need to install BTS. Each version of IV is standalone in Steam.
2) Once installed, go to BTS in the Steam Library > right click properties> Betas tab > from dropdown select "original_release_unsupported". Steam will reinstall BTS.
(note: Steam's original version of BTS included some modifications to enable their multiplayer platform for IV. However, after complaints that it conflicted with mods, Steam released the beta version to the original game specifications)
3) Always run BTS from the executable in the BTS folder (something like Programs/Steam/Steamapps/Common/BTS/BTS. Do not run from the Steam Library. You can pin the BTS folder to your quick access menu in Explorer. I recommend setting the BTS executable to "run as administrator" in Properties>Compatibility tab
(Note: That is not a mistake with BTS/BTS...there is a high level BTS and low level BTS folder. The low level is the true BTS folder and mods must be pointed there. (the high level contains the vanilla assets to make the steam version "standalone")
4) I recommend installing BUG/BULL and BAT mods which you can find here:
https://forums.civfanatics.com/threads/download-bug-and-bat-here.274636/
BUG/BULL install in custom assets (SP install mode) and is often used in forum games. Installed in custom assets means that is always present just loading the game ..no need to load a mod.. BAT mod is a standalone mod. It is basically BUG/BULL plus Blue Marble and other graphic enhancements. It's my mod of choice for casual games and can be used with any forum games that include a World Builder save.
5) In addition, you can install Blue Marble separately. It installs to custom assets and will always be present and it does not conflict with other mods. Nice graphic enhancement to the game - terrain, water, etc. In addition, you can change the color of the interface.
http://www.civfanatics.net/bluemarble/content/index.php
Note that in order to install Blue Marble for Steam BTS, the mod needs to "see" the vanilla IV executable. What I did is copied the executable over to the BTS folder. However, you would need to install IV to do that. If you don't want to do that, I will attach a copy of it here.
6) Lastly, you may at some point want to start playing HOF games and GOTM games. A mod called BUFFY is used for both. BUFFY is also BUG/BULL plus the HOF mod for checking.
http://hof.civfanatics.net/civ4/mod.php
The HOF team is in the process of releasing a final version of BUFFY soon as well to bring it up-to-date