Campaign Sets are basically a set of IL2/FB/Pacific Fighters Coop missions that have been zipped into a zip file for downloading. The missions have been generated by the Scorched Earth Campaign System and include each mission in a particular Campaign. Each of these coops are pretty exciting by themselves, but flown sequentially, they demonstrate the type of coherent Campaign that is generated by the system.

This is a great way to try out Scorched Earth and see if you like the type of missions it generates, without having to install all the software and configure it, and then learn and complete the Mission Planning.