ForceUser
Explorer
The exercise of creating the campaign world is just as fun to me as running the game. What motivates me is the desire to "get it all down," or at least enough of it that my players will feel as though they adventure in strange new lands. I love coming up with "big picture" stuff, inventing campaign-spanning plots and NPCs with longterm goals, then revealing those things little by little in-game. Yes, of course you can do such things in a published setting, but in a homebrew it's guaranteed to be new, and you don't need to worry about players who may have read DM supplements you'd have preferred they hadn't read.If you do homebrew, what gets you motivated?
The absolute BEST part of a homebrew is knowing that you are the singular authority on your campaign setting. Players don't get to crack open books and correct you about campaign particulars. They rely on you completely for setting material, which you can then dole out at a pace that suits the tempo of your campaign. Also, there tends to be less onus on the players to know things about the world, whereas in a published setting they may feel the need to read reams of book information to get a feel for things.
Finally, creation itself is just fun. Drawing maps, placing landmarks such as mountains, cities, and ruins - I find that by simply drawing a map I am charting a course for my campaign, inventing things that I can quantify and inject into the backstory. Things that I won't have to stop the game to flip through a sourcebook to recall. This is information that once invented remains with you, information that keeps the setting fresh and interesting in your mind. Players can tell when the DM is excited, and that makes the game more fun for them. For me, knowing that they are exploring a realm I created is exciting indeed.