How to create an advergame website?

Question

E.g a website like Millsberry or Neopets. What software and language would you recommend?

Answer 1

First, addressing the idea of creating an advergame, you MUST MUST MUST get permission from the company whose products you are seeking to advertise.

My recommendations would be that you use PhP for building the webpages as it is both opensource and among the best software for building dynamic webpages. To serve the pages, for an OS back end I would recommend Linux and there are several good web service softwares that you can choose.