What is your opinion about Heroes IV?

But it was already mentioned above. There was no money.

Also, Might and Magic 9 helped. Which turned out to be a huge failure in the series.

I am more than sure that they tactfully covered up the lack of money. In reality, there probably was money; for such a project as Heroes, they had to find the money... and the fact that it didn't pay off is another matter, and even this can be called a reason for the ruin only relatively, because Heroes 4 was bought by not so few people as everyone thinks...