Commander Keen 1-3

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Commander Keen 1-3
Commander Keen 1.png
Mod-Commander Keen 1-3.png
Levels?Tick.png Editable
Tiles?Tick.png Editable
Sprites?Tick.png Editable
Fullscreen?Tick.png Editable
Sound?Tick.png Editable
Music?Tick.png Editable
Text?Tick.png Editable
Story/cutscenes?Tick.png Editable
UI/menus?Tick.png Editable

Commander Keen episodes 1-3 (Invasion of the Vorticons) was a revolutionary series that launched id Software. The games made use of a number of formats and novel features that were to be adapted to other games ID produced. Commander Keen is notable for being the first side-scrolling EGA game on the PC, and for cementing id's love for EGA graphics (most previous games had CGA, EGA and VGA graphics options, all later games were EGA, or had a separate CGA version.)

In them, the hero, Commander Keen, must collect stolen parts of his spaceship hidden on Mars (episode 1), stop a Vorticon ship blowing up The Earth (episode 2) and finally storm Vorticon VI itself in search of the cause of all this trouble, the mysterious Grand Intellect (episode 3.)


The following tools are able to work with this game.

Name PlatformGroup/archives Levels Graphics Music Sounds Text Saves .exe patch Notes
ModKeen DOS consoleN/ANoEditN/ANoNoNoNo
Wombat Windows GUIN/AViewViewN/AViewNoNoNo

File formats

The following file formats are used by this game.

Filename Format Details
N/A B800 Text 4000-byte internal files are text screens shown at exit
level??.ck? Commander Keen 1-3 Level format Game levels
N/A Commander Keen EGA Header The EGA header, stored in the .exe file, is used to read graphics files
N/A Keen 1-3 Tileinfo format Information about the properties of tiles are stored internally in the executable Commander Keen 1-3 Score format High scores
save?.ck? Keen 1-3 Saved game format Saved games (Keen is one of the few early id games to allow this)
N/A Inverse Frequency Sound format PC speaker sound effects, stored in the .exe
N/A Full-screen planar EGA Most graphics are in this format, compressed or rearranged in various ways. For example, the 320x200 screen graphics are this compressed with Keen 1-3 RLE compression, the EGALATCH AND EGASPRIT files use this too. Note that the screen's plane size is 8000 bytes, 192 bytes are just 'padding'
? Keen 1-3 RLE compression This is used to compress the ending and previews screens and is a modified form of RLE.
N/A Keen 1-3 LZW compression Used in episode 1 to compress the graphics files
  • Text is contained in the executable, the executable is compressed with LZW compression, and can be uncompressed with UNLZEXE.
  • The 1.34 executable is compressed with PKLite compression; the ARCHIVE.EXE file that packages the game is a self extracting PKLite archive.


  • The so called 'Keen engine series' begins with this game. The two games based on this engine are Dangerous Dave 2 and Shadow Knights
  • Most of the file formats here were reverse engineered by the Keen modding community.

See also