A downloadable mod

KEYMASTER is a gameplay mod for GZDoom 3.0 or later that works with almost any Doom or Heretic level.

On every level a random monster is made THE KEYMASTER, tougher and faster than its comrades. Level exits won't work until you've killed THE KEYMASTER and claimed the key. But you can't damage THE KEYMASTER until you find THE ARROW OF SLAYING somewhere in the level. To find it, watch the icon on your HUD and listen for the pulse sound; it'll get quicker as you get closer.

Levels with no monsters, no pickups, or no exit switch/teleporters (eg boss
levels) will give an error and behave normally.

Configuration options are available, see the included readme for details.

CategoryGame mod
Release date May 24, 2017
AuthorJP LeBreton
Tagsdoom, mod
Average sessionA few minutes
InputsKeyboard, Mouse


doom-keymaster-mod.zip 73 kB
Version 2 Apr 05, 2019

Development log


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(1 edit)

I tried to run Keymaster in GZDoom 3.7.2, but I got 2 errors.

The Lines are 75 and 162 in handler.txt.

The result is an error "Invalid Statement".

That's why I can't run Keymaster at all.

Is there any way to fix that?

This is due to a bug in the GZDoom 3.7 series; GZDoom 4.0 was just released and does not exhibit this issue, give that a shot: https://forum.zdoom.org/viewtopic.php?f=1&t=64188