I am going to a games weekend in a few months that will culminate in a 20+ person “Grand Melee” MtG match. Each melee has a special stipulation (such as singleton format, decks cannot contain creature spells, so on) and this year is is Pauper. Due to its power in multiplayer (though in the melee you can only affect players within 2 spaces of you) and the efficiency of the commons I am expecting a lot of Extort. Can you think of any decent way of combating that, or of any other effective multiplayer pauper archetypes that might crop up?
Two great ways to combat extort are to play an aggressive deck (since extort is geared towards piecing together incremental advantage over a long game), and to play effective removal (since extort is always attached to a permanent, generally a creature). If you can either burn them out before they can stabilize, or get rid of all of their extort cards, you should be in good shape.
In terms of archetypes, I really can't help you. If there's really no restriction other than "pauper" then you're potentially looking at a widely varied pool of decks. I have no idea what you might expect.
If any of my followers know anything about multiplayer pauper archetypes, feel free to weigh in!