Megawad

A megawad is a PWAD that, according to the idgames archive definition, contains 15 or more levels.

Overview
Megawads can encompass the efforts of a single person, or the joint efforts of a entire team; this is usually done with the help of the community through specialized projects that aim to smoothen the development process, as well as allowing level authors to sign up for the project. The whole process of creating a full megawad can be daunting and very time consuming, and can be a magnum opus, for some. Because of this, megawads are given considerable attention and are often the projects most looked after, with a significant amount of projects being Cacowards winners.

Episode replacement
An episode replacement (or simply episode) is a set of fan-made levels containing a similar amount of levels as an episode of the game the episode replacement was made for. Most episode replacements therefore include eight or nine levels, which is comparable to original Doom's episode structure of eight levels and a secret level.

History
While the ultimate origin of the word will probably never be determined, the term "mega-WAD" was used by Denis Möller of The Innocent Crew in 1995 to describe the Memento Mori project. The following year, Yonatan Donner used the word "megawad" to describe his upcoming project, Hell Revealed. The word soon became commonly used within the Doom community.

SIGIL
In December 2018, John Romero announced his Ultimate Doom PWAD episode SIGIL as a "megawad", bringing renewed attention to the term, despite being technically incorrect according to the more common Doom community interpretation, which does not count a separate deathmatch arena within a level as being a separate level.

Full game replacement

 * 2002 A Doom Odyssey
 * Base Ganymede: Complete
 * Deathless
 * Doom the Way id Did
 * The Ultimate NMD
 * Wonderful Doom

Episode replacement

 * Classic Episode
 * The Classic Episode, Part 2
 * Crusades
 * Double Impact
 * Fava Beans
 * Knee-Deep in ZDoom
 * Phobos: Anomaly Reborn
 * Return to Hadron
 * Thy Flesh turned into a draft-excluder

Full game replacement

 * 10 Sectors
 * Akeldama
 * Alien Vendetta
 * Ancient Aliens
 * Back to Saturn X
 * Community Chest
 * Community Chest 2
 * Community Chest 3
 * Community Chest 4
 * Congestion 1024
 * Demonfear
 * Doom 2 the Way id Did
 * Doom 404
 * Epic 2
 * Eternal Doom
 * Eviternity
 * Going Down
 * GothicDM
 * Hell Revealed
 * Hell Revealed II
 * Icarus: Alien Vanguard
 * Japanese Community Project
 * Jenesis
 * Kama Sutra
 * Memento Mori
 * Memento Mori II
 * NeoDoom
 * Requiem
 * Resurgence
 * Reverie
 * Revolution!
 * Scythe
 * Scythe 2
 * Speed of Doom
 * Sunlust
 * Swift Death
 * Unholy Realms
 * Valiant
 * Vile Flesh
 * Whispers of Satan
 * Zone 300
 * ZPack - Random Maps for ZDoom

Episode replacement

 * Combat Shock 2
 * Dark7
 * The Darkening
 * The Darkening Episode 2
 * Dystopia 3
 * Lunatic
 * Scythe X
 * SlayeR
 * Stardate 20X6
 * Sunder
 * UAC Ultra
 * Vanguard