If anyone is interested or doubts cheating takes place on a large scale on normal difficulty, I can upload one recording, if they give me the details on how to do this and where.
Replays are selective in what they show. In the first replay it showed a Capital ship's movements, but in subsequent replays it did not. In the second save, which I can upload as an example of cheating, five Capital ships are produced from nowhere in 10 secs on Orpheus. The adjacent planet, Hesperia, shows no forces and the next planet where the rival faction is situated, Semphyra, shows, at the beginning of the recording, two Capital ships and a small supporting fleet. It is only from here can the Capital ships come from. Then a further two Capital ships are produced from nowhere in five secs, in addition to the five already produced to fight my forces. The two Capital ships are still present on Semphyra. In the third save the game actually stops me producing forces and rapidly reduces my resources in the process.
Some may think this is not an important issue, but it actually makes the whole single player game unplayable.