Developer Network
  File Specs
  Source codes
  Mailing lists
  Knowledge Base

Other Games



Descent Developer Network
Descent 1/2

Files overview


Descent files can be devided in two cathegories: One are normal files containing music, sound, graphics, level etc. information. The other file type are archives, that mean they contain many subfiles of the first type. Here I want to descripe what files and archives are known to Descent, and which files can be found/stored in which archives.

An archive is a file which contains many normal subfiles stored in one file. There are compressed archives like PKZIP, ARJ and RAR, and uncompressed ones, that just contains the data in normal form. Descent always uses uncompressed archives just because of speed.


HOG archive files

The most important and also most easy to understand file type is the HOG file. HOG files contain most of the data like the MIDI/FM musics, the briefings, the fonts, the pictures and the levels themself. Early Descent 1 versions and the Interactive Demo of Descent 2 also contain the robot data.

The normal Descent HOG file is DESCENT.HOG (all versions!). If you load a custom mission (see MSN/MN2 file) which has an own HOG all files that are missing are loaded from the main DESCENT.HOG! For example if you provide no custom music with your levels in that custom HOG Descent uses its orginal files from the main HOG! So files in your custom HOG have always a higher priority than the main HOG! This has the advantage that you do not have to provide all files with your mission (which would then explode in 5 MBs or more) but you also have the possibility to replace all files (music and so on), if you want a custom music piece or sth like that. The format of a HOG file is also relatively easy...


PIG/POG resource archive files

PIG files stored in Descent 1 information on Sound effects and textures. This was possible because Descent 1 has only used one PIG file, which was not replaceable by a custom PIG. But in Descent 2 Parallax decided to make different texture sets, one for each system (there are 6 in D2!). But as the sound effects do not change in each system this meant, that those have to be in every PIG; Descent 2 would have 35 MB more required to copy on the hard disk; 35 MB for 6 times the same data. The workaround idea was easy: the sound effects are now in external files (see S11/S22 files).

In Descent 2 you have now also the possibility to use your own texture set, to make own textures. But PIG has not the property of the HOG files: that files that do not exist in custom PIG files are taken from the original PIG file, so this will request to deliver EVERY texture with the set, which makes about 5 MB each time! So this lack was fixed with the new POG files. These are from the same format, but they only deliver NEW textures. The POG file is normally stored in the HOG file of the custom mission and is named like the level file (RL2) only with the extension POG! So Descent 2 does the following: If it finds a POG file with the same name as the RL2 it uses it, if not, nothing changes... So it stays compatible to older Descent 2 versions, which will just ignore POG files! Descent 2 V1.0 and V1.1 are the versions which do not use POG files, V1.2 is the first which uses it! Note: Nothing in the RL2 file actually indicates that there are custom textures, only the presence of a POG file does that!


S11/S22 sound archive files

These files contain the sound effects for Descent 2! Descent 1 has them all in the PIG, but as Descent 2 provides multiple texture sets with own PIGs each, the sound effects would have been in every PIG file which means that you would loose much hard disk space!

The DESCENT.S11 file contain the 11 kHz sound version, which is only played when you start Descent 2 with the -Force22k switch or when you have a slow 486 computer, as 11 kHz sound costs less processor time. The S22 file has the same effects but in 22 kHz quality!

These files are not replaceable in custom missions! That means if you want to change a sound you have to do it global, that means, every mission will have the new sound then! However it seems to be that Parallax will implement custom sound in one of the next updates, but I'm not sure about that!

The format in itself is not put in a spec till now; fact is that the sound data itself is saved in raw data.


HAM/HXM resource archive files

The HAM file is quite a serious thing till now! It has all vector datas of the robots and the ships in it, it also has the AI routines and the robot behaviour in general saved in it, but there seems to be even more!

Note that HAM files are only existing in Descent 2, as early Descent 1 versions and the Descent 2 Interactive Demo uses single files named POF in the HOG archives, and Descent 1 V1.4 and higher seems to have this data in the PIG file...

There is also a new file format which replaces robots in custom missions! This format is called HXM and does the same as POGs do to texture sets (PIG)! This means if in a HOG is a HXM file which has the same name as the RL2 file, it replaces the information stored in the HAM file as far it is provided in the HXM file! All other info is got from the HAM file!

But it seems as another HAM file can be used parallel to the original DESCENT2.HAM! The Vertigo Series uses this to bring the new robots! That new HAM file is stored in the HOG file of the Vertigo Series levels (D2X.HXM)! Also the Hoard informations (sounds and textures) is saved in a HAM (HOARD.HAM)!


MVL movie archive files

The MVL file contains multiple movies. As HOG saves all file types, MVL is specified for movies only! However the format itself would support even other file types!

  • MVL specs
  • Note that there was a tool to extract and play MVE and MVL files called Descent Manager MVEEXTRACT32. However the tool had to be removed from our pages due to copyright problems with Interplay.


Other files

Lists of other file types in Descent 1/2:

See HXM specs.
*.256 Stored in HOG Palette files
256 specs
*.BBM Stored in HOG Texture files for end-sequences (Descent 1 and Descent 2 Interactive Demo only)! Format is the same as it was used on the Amiga (LBM) and can be read by various pic viewers!
*.HAM Stored in HOG Robot information add-ons (used as so-called V-HAMs).
V-HAM specs
*.HMP Stored in HOG MIDI Music files used on Wavetable soundcards.
MIDI2HMP - MID->HMP converter
DTX/DTX2 - two-way converter (for MID->HMP conversion, MIDI2HMP is recommended)
*.HMQ Stored in HOG MIDI Music files used on FM soundcards.
*.HXM Stored in HOG Robot information replacements.
HXM specs
*.MID Stored in HOG MIDI Music files for Windows 95 version!
*.MVE Stored in MVL Single-movie files including sound.
*.POF Stored in HOG Older Descent 1 versions and the Descent 2 Interactive Demo uses these files for robot and powerup information.
*.POG Stored in HOG Texture replacements. See PIG/POG desc. above!
*.RDL Stored in HOG Descent 1 Registered Level files.
RDL specs
*.RL2 Stored in HOG Descent 2 Registered Level files.
RL2 specs
*.SDL Stored in HOG Descent 1 Shareware Level files.
*.SL2 Stored in HOG Descent 2 Interactive Demo files.
*.SNG Stored in HOG MIDI Music directory. Defines which file is played when.
*.TEX Stored in HOG Briefings in uncrypted form.
TXB specs
*.TXB Stored in HOG Briefings in crypted form.
TXB specs



All pages (C) 1996-2000 Descent Network Team
Everything taken from the Descent, FreeSpace, Red Faction and Summoner series games are
Copyright Interplay Productions , THQ Inc. , Parallax Software , Volition Inc. and/or Outrage Entertainment