Guys - apologies if you dont like the title, but the statement holds true.
While one is getting the Error 28 on boot up, one can go no further and Civ 3 is effectively dead. There is no support in game or from firaxis as obviously they look at Civ 6 only.
So taking the 'fixes' described elsewhere and in post above, changing FOT file name, it then came up - on boot up of game on C3C disks, with error 13.
The game had been working perfectly for months on a new computer, so I felt it was not caused by a hardware glitch.
I then taking advice from a post above, repurchased the game on stream.
VOILA - same problem - back to error 28.
Gave up and walked away from game for a few days. But mulling over a comment above about what did I change, i realised that it might be - what did I not change/do. I have been on windows 10 for months, but hearing issues mentioned by others about the latest windows 10 update, I had not run the update. With the trouble I had with Civ, I wondered if it was a windows problem... so I ran the update, and next day reloaded Civ 3C.
It now works....
SHould the issue raise itself again - I will take screenshots for you, but essentially it just tells you that Error 28 and the the game is shutting down.
Maybe this should go back where it was as it can now bring hope to others who have the problem as it is very very frustrating when it occurs.....
PS - no issues yet with windows 10 upgrade either....
