I wrote a short supplement for The Nightmares Underneath that has Powered by the Apocalypse rules for players to use, for those of you who prefer that style over the old school D&D-ish rules. It is called A World Full of Nightmares, and it includes:
- a set of basic moves;
- new rules for harm and disposition, experience, and money that are more like Apocalypse World;
- simple character classes with simple special abilities (but you can add special moves from Dungeon World or Class Warfare if you like);
- conversion rules for the nightmares curses;
- a simple GM section;
- a new more-narrative-y system for creating incursions that you need a deck of cards for.
A World Full of Nightmares is now included in the full pdf version of The Nightmares Underneath. If you have already purchased it, simply download the new updated zip file. A staple-bound print version of A World Full of Nightmares is available from Lulu for US$10.