The Pandemic: On the Brink rulebook has been uploaded to BGG.
On the Brink is an expansion for Pandemic designed by Matt Leacock and Thomas Lehmann (of Race for the Galaxy fame). It brings several new roles one of them being the bio-terrorist (which seems to have similarities with Dracula from the Fury of Dracula as players have to guess his location) and a revised Operations Expert, the possibility to play with up to 5 players, a new disease and 3 different new challenges.
From the component side, the game comes with 12 pawns (which I guess half come to substitute the first edition ones), purple disease markers, new special event cards, virulent strain cards, blank card to design your own cards and Petri dishes with labels!
The expansion seems to complicate the game a lot (rules and play wise), I’m sure some people will miss the simplicity of the base game, but then again those weren’t the people this expansion was made for clearly.
On the Brink will be availably in June.
Tiago is the mastermind behind Breaking the Magic but he usually isn't the mastermind when playing games getting a lot of humiliating last places. He is however a cunning Cylon. Also never ask him to roll a die, even though he doesn't have bad luck at critical times he is known to roll the worst possible result. He loves receiving mail and answers every single one. 
