Burning MUD has an entirely custom OLC (On-Line Creation) tool, which allows an author to build an entire zone in-game, and test it as you go. Intuitive commands allow simple ways to build rooms like walking in the desired direction to create a new room there, and a simple menu system that allows you to choose relevant values for your creations, as well as auto-calculating values for mob stats based on the level you define, which lets you focus on customization rather than the tedium of filling out basic numbers.
We have a high standard of quality for zones, and we will be glad to assist you in making sure your zone fits as a part of the world and has a special place in the game, as well as helping with game balance and Mobprogs to make sure your creation is polished and shines how you want it to!