$OpenBSD$

A valid Doom, Doom II, Final Doom, etc IWAD is required for use of this
engine.   There are some options via the ports tree:

- games/doomdata   # Doom: Shareware
- games/freedoom   # Free re-implementation of all game assets

A stunning example of Eternity Engine's features is the vaprdemo mod:
http://eternity.mancubus.net/vaprdemo.zip  (Requires Doom 2 IWAD)