Game design from the beginning

[JonO]

I would argue that if it is too large to put in words, it is far too ill-defined to put into code. The iterative pattern you describe works well, though I prefer to work as modularly as possible, too. Back in the good old days of the 640K barrier, we were forced to program in modules and therefore to think that way. One module for transfer, another one for buy, and a third for selling, etc. And thinking that way is a good method of breaking down your design into smaller, more easily defined concepts that will allow the designer to dig down until he got a real, robust, framework.