I am giving myself a crash course in VB with VS2005. Once I get the ropes down I was wondering if such a concept is possible;

Creating a module that in effect works like a old school BBS door game. Start of with something simple like a basic ANSI D&D type game where registered members can fight monsters and each other. I suppose you could see it as a MUD style of game module as well. Is that kind of idea possible module/DNN wise?

you can write an asp.net game in visual basic and use Open Smart Module to create your own module if you want.

I would suggest using Silverlight. It is great for games. It is easily incorporated into DNN and it will work on the Mac and Linux.