I think I've played through most of the dungeons by now, and I believe I have all the Kingdom buildings. But I still just have three gods whose altars spawn, Taurog, Tikki Tooki, and Glowing Guardian. How do I unlock the other gods (Mystera, Dracul, Pactmaker, Earthmother)?
I've now located Mystera and Dracul. I'm not sure Pactmaker and Earthmother are in the game yet, since I haven't seen them mentioned in the patch notes at all.
Each god has a subdungeon associated with them, where you must complete some requirement in order to unlock them. We aren't entirely sure what causes the subdungeon to appear, it seems to be random at this point. The answers currently list at least one place where the subdungeon can appear.
Unfortunately I can't remember where exactly I found the others, so I'm making this CW so someone else can add them.