An advanced DOOM source port maintained by James "Quasar" Haley, descended
from Simon "fraggle" Howard's SMMU. It has a whole host of advanced features
for editors and players alike, including:

- ACS, including many of ZDoom's enhancements
- EDF, Eternity Definition File, a language to define and modify monsters,
  decorations, sounds, text strings, menus, terrain types, and other kinds
  of data.
- ENDOOM and animated startup screen support.
- High-resolution support (practically unlimited).
- Support for Master Levels and No Rest for the Living, allowing to play them
  without command line options.
- Portals which can be used to create skyboxes and fake 3D architecture.
  Linked portal allow objects to pass through them, as well.
- PNG support