How To Make A Website Like Poptropica?

I think you can easily make such a website with the help of some templates for Wordpress like those from https://www.templatemonster.com/category/cafe-restaurant-wordpress-themes/ Take a look at those, I am pretty sure you will find something for you there

Use some templates like it, and you will be fine

I do not know about making a site like Poptropica, but you can make a site at ning.com I think.