Homebrew

When you're starting a homebrew D&D campaign — building your own adventure in your own world — it's okay to not have everything planned out in advance.

When you're planning to write your own unique Dungeons & Dragons campaign rather than a pre-made, fully-realized campaign -- also referred to as homebrew -- it can be incredibly fun to go hog wild on the worldbuilding.

There is a new Unearthed Arcana come out for Dungeons and Dragons, Travelers of the Multiverse.

There are a lot of excellent Dungeons & Dragons setting books out there that will give you all the details you need to run a game in their setting, and those settings (also known as campaign settings, world settings, campaign worlds and/or simply campaigns) are often excellent.