It's written completely in DM and uses simplistic commands and features. I think that I'll be working on this for a good while making sure that the functionality and bugs are all ironed out.
Also there's a bit of a backstory on how the beginning of developing this came to be.
Edreoll is under works too. I've been working on the editor for that a couple of days ago. It will use custom files for loading maps, items, etc instead of relying directly on datum types like "/obj/item/equipment/sword1".