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For more information on this article, visit the GrbDoom page on the Doom Wiki.

GrbDoom was a unfinished source modification of ZDoom 1.20. It introduced several new features that changed weapon and monster attacks extensively for experimental purposes by its creator, Grubber.


The first release was based off ZDoom 1.20 and was a private release build done in either 2003 or early 2004. It remained unreleased till January 2021. The first public reveal was on June 1, 2004, when Grubber revealed GrbDoom, as version 2 with a build date of May 30, 2004. It was upgraded to ZDoom 1.23 beta 33. It implemented a new menu, Grubber Options, where the behavior of the players weapons can be changed and where also the monster's modi of attacks could be changed simultaneously.


GrbDoom implements a new menu entry called Grubber Options. These consist of the following submenu's:

Weapon options

Weapon options alter the properties of the player's weapons. Multiple changes can be active at the same time.

Monster options

Monster options change the weaponry of the monster's weapons. The cycle speed on which the weapons fire is retained. Multiple changes can be active at the same time.

Behavioral changes can be stackable. For instance, a Hell knight can be changed to fire a lost soul that can shoot a BFG blast. Similarly, a lost soul can be changed to summon a lost soul, which summons another lost soul indefinitely. Through these parameters, a large range of combinations are possible. All monster and weapon behavior can be changed simultaneously and dynamically, as in, a restart of the map is not required for the change to be made active.

Demonstration map

The GrbDoom package includes a WAD called pyramid.wad. It features a demonstration map that includes the following:

  • The level features a giant pyramid from which multiple monster spawners generate new monsters that roll off the sides of the pyramid
  • Transparent monsters that fade in and out of visibility
  • A static cannon that can shoot cannonballs with the power of a rocket towards enemies, essentially functioning as a turret


In early May 2020, the author of the modification was approached through a private message on the ZDoom forums. When initial responses panned out, a public request was made in late May requesting retrieval without success.

On December 7, 2020, Grubber released version 1 of GrbDoom on GitHub, before publically releasing the latest version on January 2, 2021. The old source code was retrieved and a fresh compilation of both versions was made by Grubber before hosting it on GitHub.

External links