Hacx (pronounced "hacks" and commonly written as HacX) is a total conversion for Doom II. It was created by Banjo Software on September 16, 1997, and featured an entirely new set of graphics. Hacx uses a DeHackEd modified version of the Doom engine and the authors of Hacx paid id Software $5,000 for the rights to market Hacx as a commercial add-on for Doom II.
Hacx itself was generally unsuccessful; by the time it was released, the superior Quake engine that had just come out made the Doom engine pale in comparison. Public interest for Doom and games derived from it was, effectively, dead; even though Hacx was considered a decent TC, it arrived on the market too late to become a success.
Hacx was originally priced at $14.95 on a CD-ROM, and $20.95 on diskettes. The sprites and other graphics from Hacx have been reused in many other TCs/PCs since, despite Banjo Software having forbidden the use of Hacx's resources in other WADs.
Hacx is now being distributed for free on its website kept online by Rich Johnston (Nostromo), one of the developers. The Hacx CD and disks are considered to be extremely rare.
Despite the game's commercial failure, some of its creators have since become successful and relatively well-known professional game developers. Iikka Keränen (Fingers) went on to work at Looking Glass Studios, Ion Storm, Ritual Entertainment, Rogue Entertainment, and most recently, Valve Software. Kenneth Scott has since worked as an artist at Ion Storm and id Software. Later, he was employed as the art director at Microsoft Studios for Halo 4 (2012). Zach Quarles went on to work at Raven Software and id Software. Kevin Johnstone is currently employed at Epic Games.
Hacx 1.1 was the first free release of Hacx. The release was not an update from 1.0, but rather a downgrade to some version in the development history. A few differences include MAP15 and MAP14 being swapped. As a result, the proper secret exit was removed and the game always goes to MAP31. MAP10 also had a terminal entrance similar to MAP05, but was removed. Likewise, the exit room for MAP19 was removed.
As a platform upon which to build Hacx 2.0, a 1.2 update of the original Hacx was released on October 9, 2010. The changes included making it as a stand-alone IWAD recognized by Chocolate Doom, Crispy Doom, Doomsday, EDGE, Eternity, GZDoom and ZDoom, but still compatible with other source ports (and even vanilla Doom if the DeHackEd lump is extracted and used for patching).
A 1.3 update isto fix a few bugs.
In November 2008, Nostromo declared on the Hacx homepage that a new version of Hacx is being made. The comment stated:
Believe or not, after nearly 10 years since Hacx has been released, a version 2.0 is currently in production! As many of you may have noticed, the original game was released as, shall we say, a not quite complete product. This was due to the fact that we had to rush it to the market before the Quake engine came out ...not that it made any difference, unfortunately.
Recently, I was contacted by an individual that goes by the online name of Xaser who was real excited about making a complete version for the ZDoom engine. He provided an updated script for all the maps and, based on his awesome enthusiasm and remarkable reworking of the script, I gave him the go ahead to build away. He is currently working on some maps and building a team.
Hacx has been ported to these platforms, based on the Doom Classic code, by the same company that also did one of the commercial Freedoom ports. Contrary to "Doomsday: Hellraiser", however, "Hacx Classic" is available for free, as the license for the Hacx content does not allow commercial distribution.
- Android (replaces Shotgun guy)
- Buzzer (replaces Demon)
- D-Man (replaces Lost soul)
- ICE (replaces Imp)
- Majong 7 (replaces Pain elemental and Mancubus)
- Mechamaniac (replaces Hell knight)
- Monstruct (replaces Heavy weapon dude)
- Phage (replaces Mancubus)
- Roaming Mine (replaces Wolfenstein SS)
- Stealth (replaces Spectre)
- Terminatrix (replaces Baron of Hell)
- Thorn Thing (replaces Arachnotron)
- Thug (replaces Zombieman)
- Unnamed invisible enemy
- Kevlar vest
- Super kevlar vest
- Body armor
- Light amplifier goggles
- Enk blind
- Vulcan rubber boots
- Force field
- SI array
- Molecule module
- Case of cartridges
- Case of rounds
- Case of torpedoes
- Molecule tank
- Blue Z-Key
- Red Z-Key
- Yellow Z-Key
- MAP01: GenEmp Corp. by Michael Reed and John Herndon
- MAP02: Tunnel Town by Stephen Watson
- MAP03: Lava Annex by Marc Pullen (Fanatic)
- MAP04: Alcatraz by John Herndon
- MAP05: Cyber Circus by Iikka Keränen (Fingers) and John Herndon
- MAP06: Digi-Ota by Stephen Watson
- MAP07: The Great Wall by Adam Williamson
- MAP08: Garden of Delights by Ryan Rapsys
- MAP09: Hidden Fort by Anthony Czerwonka (Adelusion)
- MAP10: Anarchist Dream by Ryan Rapsys
- MAP11: Notus Us! by Michal Mesko (msquid)
- MAP12: Gothik Gauntlet by Rich Johnston (Nostromo)
- MAP13: The Sewers by Anthony Czerwonka (Adelusion)
- MAP14: 'Trode Wars by Andrew Gate (Xenos)
- MAP15: Twilight of Enk's by Jeremy Statz
- MAP31: Desiccant Room by Stephen Watson
- MAP16: Protean Cybex by Marc Pullen (Fanatic)
- MAP17: River of Blood by Marc Pullen (Fanatic)
- MAP18: Bizarro by Anthony Czerwonka (Adelusion)
- MAP19: The War Rooms by Adam Williamson
- MAP20: Intruder Alert! by John Herndon
The cheat codes for Hacx are different from the ones in the original Doom. 
- wuss - toggles God mode
- blast - keys, all weapons, full armor and ammo
- zap - taser
- seeit - power-up menu
- superman - toggle temporary invincibility
- whacko - berserk
- ghost - toggle temporary partial invisibility
- boots - toggles boots
- bright - toggles light amplifiers
- walk - toggles clipping
- warpme## - jump to level ##
- where - gives full automap
- wheream - shows coordinates
- show - toggle map detail
- tunes## - change music to level ##
- Hacx's modified executable is called DHACX.EXE. It consists of a DOOM2.EXE version 1.9 based executable merged with HACX.DEH.
- Both the installation and files only versions of Hacx 1.1 contain a DHACX.EXE that is unable to play back demos from each other. Only the installation version can play back demos made with that specific executable, but not those of the files only version. The files only version cannot play back demos unless the executable from the installation version is used. A separate DeHackEd patch called HACX_F.DEH exists, made by Graham Burgess (Grazza), enabling playback with the files only version of Hacx.