diff --git a/engine/MUNGA_L4/L4AUDRND.cpp b/engine/MUNGA_L4/L4AUDRND.cpp
index 8e3415b..a1b5a71 100644
--- a/engine/MUNGA_L4/L4AUDRND.cpp
+++ b/engine/MUNGA_L4/L4AUDRND.cpp
@@ -383,9 +383,22 @@ void
 		ALCcontext *context = alcCreateContext(device,NULL);
 		alcMakeContextCurrent(context);
 		// Master volume: AL_GAIN on the listener scales EVERY source.  Default 0.6
-		// (the raw samples are hot); override with BT_AUDIO_VOLUME=<0.0..1.0+>.
+		// (the raw samples are hot).  Priority: BT_AUDIO_VOLUME env >
+		// content\volume.cfg (written by the runtime -/+ keys, issue #26) > 0.6.
 		float masterVol = 0.6f;
+		{
+			FILE *cfg = fopen("volume.cfg", "rt");
+			if (cfg != NULL)
+			{
+				float f = -1.0f;
+				if (fscanf(cfg, "%f", &f) == 1 && f >= 0.0f && f <= 1.5f)
+					masterVol = f;
+				fclose(cfg);
+			}
+		}
 		if (const char *v = getenv("BT_AUDIO_VOLUME")) { float f = (float)atof(v); if (f >= 0.0f) masterVol = f; }
+		extern float gBTMasterVolume;
+		gBTMasterVolume = masterVol;
 		alListenerf(AL_GAIN, masterVol);
 		if (getenv("BT_AUDIO_LOG")) DEBUG_STREAM << "[audio] OpenAL device OPENED + context current; master gain=" << masterVol << "\n" << std::flush;
 		// (task #50, AUDIO_FIDELITY F9/F11) EFX bridge: the authored lowpass
@@ -1442,3 +1455,31 @@ void L4AudioRenderer::ReleaseSourceSet(SourceSet &sourceSet)
 #if defined(TRACE_AUDIO_RENDERER_DORMANT_SOURCES)
 	BitTrace Audio_Renderer_Dormant_Sources("Audio Renderer Dormant Sources");
 #endif
+
+//
+//#############################################################################
+// Master-volume runtime control (issue #26, 2026-07-23).  The pod had a
+// physical volume knob on the operator side; desktop players had NO way to
+// duck the (hot) game audio under voice chat short of the Windows mixer.
+// The -/= keys step the OpenAL listener gain (the master scale for every
+// source); the value persists in content\volume.cfg (CWD) and reloads at
+// the next boot (BT_AUDIO_VOLUME env still wins when set).
+//#############################################################################
+//
+float gBTMasterVolume = 0.6f;
+
+void BTAudioMasterVolumeStep(int direction)
+{
+	gBTMasterVolume += (direction > 0) ? 0.05f : -0.05f;
+	if (gBTMasterVolume < 0.0f) gBTMasterVolume = 0.0f;
+	if (gBTMasterVolume > 1.5f) gBTMasterVolume = 1.5f;
+	alListenerf(AL_GAIN, gBTMasterVolume);
+	FILE *cfg = fopen("volume.cfg", "wt");
+	if (cfg != NULL)
+	{
+		fprintf(cfg, "%.2f\n", gBTMasterVolume);
+		fclose(cfg);
+	}
+	DEBUG_STREAM << "[audio] master volume "
+		<< (int)(gBTMasterVolume * 100.0f + 0.5f) << "%" << std::endl << std::flush;
+}
diff --git a/game/reconstructed/mech4.cpp b/game/reconstructed/mech4.cpp
index 12cc607..7aee087 100644
--- a/game/reconstructed/mech4.cpp
+++ b/game/reconstructed/mech4.cpp
@@ -2746,6 +2746,24 @@ void
 					// task #12: Generator1-4 actions assign the selected weapon
 					// to Generator A..D; Reconnect toggles Manual/Auto.
 					gBTGenSelKey      = gBTInput.genSel;
+					// issue #26: -/= step the master volume (edge-detected;
+					// VK_OEM_MINUS/VK_OEM_PLUS, focus-guarded like all polls).
+					{
+						extern void BTAudioMasterVolumeStep(int direction);
+						static int sVolDn = 0, sVolUp = 0;
+						unsigned long fgpid = 0;
+						if (GetForegroundWindow() != 0)
+							GetWindowThreadProcessId(GetForegroundWindow(), &fgpid);
+						int focused_vol = (fgpid == GetCurrentProcessId());
+						int dn = focused_vol
+							&& (GetAsyncKeyState(VK_OEM_MINUS) & 0x8000) != 0;
+						int up = focused_vol
+							&& (GetAsyncKeyState(VK_OEM_PLUS) & 0x8000) != 0;
+						if (dn && !sVolDn) BTAudioMasterVolumeStep(-1);
+						if (up && !sVolUp) BTAudioMasterVolumeStep(+1);
+						sVolDn = dn;
+						sVolUp = up;
+					}
 					// task #13: the Valve action cycles the coolant valve.
 					gBTValveKey       = gBTInput.valve;
 					// Gitea #7: the Flush action HELD = the coolant MFD's
diff --git a/players/README.txt b/players/README.txt
index 0bcae9c..259a179 100644
--- a/players/README.txt
+++ b/players/README.txt
@@ -41,6 +41,7 @@ CONTROLS (keyboard):
   1 or Space ........... main trigger          2 ............. middle thumb
   3 or Ctrl ............ upper thumb (missiles) 4 ............ pinky
   V view | B look-behind | M control mode | N schematic | J/K/L MFD pages
+  - / = ................ game volume down/up (saved between sessions)
   G (hold) + fire key .. regroup a weapon onto that trigger -- or hold a
      weapon panel's red PROGRAM button with the mouse and tap a fire key;
      the joystick diagram on the panel shows the binding live.