An interview on Gamasutra talks with Super Meat Boy co-creator Edmund McMillen about Binding Of Isaac, revealing plans for The Wrath Of The Lamb, an upcoming expansion for the "roguelike-like" game. Here's word on the add-on, which is due when it is done:

My goal is to try to trick myself, once again. I wasn't entirely happy with the game until I was able to trick myself with the random elements and happenings, so I wanted to add so much more. There obviously is going to be more of the same, I think I added 50 items, 20 trinkets (which are a whole new set up), and then as much rare and random happenings as possible.

There's basically two paths, there's an alternate chapter per chapter. What I've shown is the cellar, which is an alternate to the basement. So you could start your game, and it might be cellar 1, which has different enemies, different rare rooms, different bosses, different random happenings that are going to be new to the mix. Then the next level you might be in basement 2, or maybe the next level you'll be in cellar 2. It'll just choose randomly from those.