I've been playing one of the zygna games myself.
To the level I've got, plenty of things would be easier if I was willing to spend money, but I haven't found anything I can't do for free.
To the level I've got, plenty of things would be easier if I was willing to spend money, but I haven't found anything I can't do for free.
To generalize it, its easy to get a handful of people to do something. If you offer it to them for free, there are plenty of people who will go out of their way to advance as far as possible. Once those people start getting friends involved, the friends will want to get that far too. By offering them a quick advancement in exchange for money, you can then make a tidy profit.