Megawad

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

Megawads may be the effort of one person - such as Thomas van der Velden's Revolution!, Erik Alm's Scythe series or Gwyn Williams's Vile Flesh - or of many people, such as the Memento Mori series, the Alien Vendetta megawad or the Doomworld Community Chest series. Whether a solo or group effort, excellent megawads require a huge time investment and can require months or years to create. A megawad may also represent a Doom mapper's collective lifetime works, such as Jan Van der Veken's Classic Episode, being a collection of levels previously released as stand-alone PWADs.

Because a megawad is such a massive undertaking, quality megawads are few and far between. However, they are almost always the most anticipated PWAD releases, as well as the best remembered.

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. By 1996 Yonatan Donner used the word "megawad" to describe his upcoming project, Hell Revealed. By 1997 the word was in common usage within the Doom community.

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.

Full game replacement

 * 2002 A Doom Odyssey
 * ConC.E.R.Ned
 * Doom the Way id Did
 * Base Ganymede: Complete
 * Wonderful Doom

Episode replacement

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

Full game replacement

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

Episode replacement

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