That was the No CD patch I got but I cant get it to work with the steam version
OK, then perhaps this is a "Virtual Store"-related problem?
IIRC, the Steam games-folder is installed by default into a subdirectory of the (very important) C:/ProgramFiles
system-directory, but (if I have understood correctly) modern versions of Windows (since Vista) don't allow 'unauthorised' programs to write to — or, more importantly, be run from
— that directory. Instead, Windows places only a virtual image of any such file in that directory, while actually
quietly storing the file itself in a mirror-location, elsewhere on your HDD.
That is, while it might look
as though the NoCD .exe is in your Civ3 folder, it's not really there (since it was not installed by the authorised Steam-client) — which might be why it now can't find your Civ3Complete installation. If this is the problem, though, I'm not 100% sure how you'd get around it.
For example, you would almost certainly need to have Admin rights on your machine in order to properly write the NoCD .exe into ProgramFiles/.../[SteamGames
]/ to begin with, and you might also have to set the file itself to "Run as Admin" — but I'm not sure whether e.g. Win10-11 will allow you to do either of those things.
(I know I can do both those things on Win8.1, but I also
deliberately installed Civ3 outside ProgramFiles in the first place).
Setting the NoCD file's compatibility to WinXP SP2 (or SP3) may also be needed.