Like many in the early 80s, I moved from the B/X version of the World's Greatest Game to the Advanced version. But also like many, I never forgot my "Basic" roots and thought for all it's "Advancements" there was still something special about the Basic game.
Well OSE hears you. The modular design of OSE makes adding material that is considered "Advanced" to be quite easy. Granted this is not the first Retro-Clone to do this, but this one does it in such an elegant fashion.
Advanced Fantasy: Genre Rules adds new classes and new races. For new races we get drow, duergar, gnome, half-elf, half-orc, and svirfneblin (yes deep gnomes!) Also true to the advanced rules this book pulls race and class apart. In truth this was one of the major benefits of the Advanced game and that is true here as well. For new classes, we get acrobat, assassin, barbarian, bard, druid, illusionist, knight, paladin, and ranger. There is also rules for multi-classing, something I always want to add to my basic games. Some additional rules on poison and magic are also included.
A fantastic addition to the Core Rules.