Pokemon FireRed and LeafGreen
These two games are the revamps of Pokemon Red and Blue. It is the same main story line but a lot of the trainers and their Pokemon have changed. There are also many additions like a whole addition to the storyline. After you defeat the Elite 4 and recieve the National Dex (catch 60 Pokemon), you get access to the Sevii Islands where you can catch new Pokemon and eventually connect up to Pokemon Ruby, Sapphire, and Emerald.
In FR and LG you are brought back to the original 151 Pokemon and after the Elite 4 and National Dex, you can get some Johto Pokemon (Pokemon Gold, Silver, and Crystal) and of course as I mentioned before, link up to RSE.
If you loved the original games, Pokemon FireRed and LeafGreen are for you because you'll get the same as before, but much much more! Not to mention better graphics. :P