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ObHack is my name for some modifications Fritz and myself have made to Oblige, a random map generator for the original Doom, Doom 2, and Heretic. It is name thusly because it is a hacked Oblige, and as a tribute to the ObHacks posted to the once-great Usenet newsgroup alt.hackers.

ObHack is a fork of version 2 of Oblige (Oblige 0.81-0.97). It has the following features that Oblige2 does not have:

  • Real secret areas that take work to find
  • Improved random number generator which allows arbitrary English or Spanish text to be the seed, resulting in a nearly infinite number of possible seeds
  • New modes: Single Player + Deathmatch, Deathmatch without exits, and Capture the Flag
  • Progressive level size: Levels get bigger as one gets to higher levels in the wad
  • Enclosures and variable room sizes
  • Adjustable light level
  • Tiny and gigantic level sizes
  • Option to have swarms or even more monsters
  • Monster traps are back (removed in Oblige 0.94)
  • Boss levels now have boss monsters in them
  • Choice of player starting weapon
  • More texture packs, including contributions from Mr. Chris
  • Deathmatch starts in single player maps
  • Support for Blasphemer 0.1
  • And other features not listed here

Git repo

ObHack is currently in deep freeze; development is focused on adding tests to the code base and making it more deterministic. There is a Git repository for ObHack at GitHub, GitLab, Bitbucket, and Sourcehut.


Most people will want to download the final version of the ObHack-8 fork of ObHack:

“Hockey Rink” Version

The most recent updates are done to an older version of ObHack, based on the 2009 code base. I use this older version because it’s more compact than more recent versions; this is a size optimized release for fitting on a “hockey rink” business card sized CD.

This release also includes my fork of an older version of FreeDoom.


Since I am not getting paid for this work, and since professional support contracts cost tens of thousands of dollars a year, the amount of support I provide for ObHack is very limited. I do pay attention to ObHack bug reports filed in GitHub, but I am under no obligation to answer or even address your concern.

Please do not send me a private message asking for support; if you do, I will refer you to GitHub.

Older releases

Older releases of ObHack (and SLUMP) can be seen here.

Other files

Here is a local mirror of all Oblige releases.

There is also version 1.8.6 of the Doomsday/Dengine engine for playing Doom. Please note that this version of Doomsday does not work with newer (post-0.7) releases of FreeDoom. Be aware that I do not provide any support for Deng 1.8.6 besides having a download; people who want a supported version of Doomsday should go the the Doomsday website and download the latest version there.

See also

Here is a Doom random map generator being updated: