Often we start the campaign of broodwar and find us in a situation, where we cant pass a mission because the Ai is overpowered. After many years we finally beat it and find us alone with a big void. Than we start for more content in form of new campaigns and more content.
If that is the case you may find the search option at the right top, left of the portrait, very usefull.
There are lists of custom campaigns, one of them is in SEN and the other one is in Pronogo’s wikidot.