Aeric
Explorer
My last campaign developed a theme. The PCs kept breaking seals and letting things into the world that shouldn't be there. I was co-DMing the campaign with another DM, and we hardly ever compared notes since we each played while the other ran, so it was a coincidence. Once he stepped down as co-DM (leaving me to run the game by myself), I took the idea and ran with it, explaining that the seals themselves were weakening due to the world itself unraveling. Once we got into epic levels, I was going to reveal that some rogue demigods were behind the unraveling, trying to "recycle" the world for raw materials for a new world of their own creation. We never got that far, unfortunately. 
