My first question would be whether the game is going to have a web based UI or be some kind of console/window affair like the original Rogue-like games? If the former I would say that any language you're comfortable with would be a good choice. Ruby on Rails, Python/Django, PHP/CakePHP, etc. would all be great.
But if the answer is the latter, this is a game that you want people to be able to download and install locally, I'm going to go with Java. It's a great language with no memory management for you to deal with. It achieves very high performance thanks to just-in-time compilation and optimization, and it has an extremely rich library to help you with data structures, Swing makes for some really beautiful UIs, and the 2D library allows for the most rich cross-platform rendering outside of PostScript. It also has the availability across Windows, Mac OS X, and Linux that you're not going to get from some other choices.
Finally, distribution of your application is easy via Java Web Start as well, so people can download and install the game with just a couple of clicks once they have Java and keep it on their machine to run as long as they like.