Fallout: Atomic BondsExpansion

From BoardGameGeek:

Sometimes in the Wasteland, things can get lonely. After all, you're wandering across an irradiated hellscape, taking potshots at passing ghouls and eking out your best existence. But maybe you don't have to be alone! Maybe, just maybe, you'll find a few people out there who want to stick around for a while. You might even accomplish something great together. With the Atomic Bonds Cooperative Upgrade Pack for Fallout: The Board Game, the number of scenarios available to you just doubled. This upgrade pack has everything you need to play every competitive scenario from Fallout: The Board Game and the New California expansion as a cooperative scenario. Rather than struggling against each other, Atomic Bonds lets you and your friends travel the Wasteland, grab the best gear, and push your chosen faction to victory-together! Combine that with the addition of modifications, mutations, and workshop upgrades, and Atomic Bonds pushes your games of Fallout to dizzy new heights. -description from the publisher