Pandemic: On the Brink adds new roles, new variants, and new diseases to the Pandemic game.

New roles include the Archivist, The Generalist and the Bio-Terrorist. That's right, you can even play against this role while fighting the game itself. Variants include mutations, 5th player rules, and new special events to add to the game. A 5th disease can be added to the game under some variants. What's cool is that you can mix and match the variants, rules, roles, etc.

Finally, it includes petri dishes to hold the disease cubes with stickers so people can name their own diseases.