Slitherine

I have enjoyed playing Onslaught, and how it is slightly different each game and especially by varying which General you choose at the start. Right now, I have two choices: THE CURSE, and THE AMULET OF POWER. But it looks like there are more. Today I spent awhile trying to figure out how to buy those but I just don't see them advertised. Can someone answer: are those the only two campaign choices? Are the designers going to add more? If there are more, what is a link to get them as I've looked on Steam and Slitherine and just don't see any. Thanks!