From the Pulisher's Website:
6-Pack adventures is a new venture for Postmortem Studios into the field of adventure support and writing, 6-Packs will turn up for various different open systems but they all share the same design goal, to create an adventure that can be picked up and played in an evening with everything already done for you. A sort of ‘takeaway’ convenient, short adventure that you can slot into your regular gaming space, run as a demo or at a con without any real preparation.
6-Pack Adventures are ‘pick-up and play’ adventures