diff --git a/RP_L4/RPL4.CPP b/RP_L4/RPL4.CPP
index 947fb2a..bfa2ba7 100644
--- a/RP_L4/RPL4.CPP
+++ b/RP_L4/RPL4.CPP
@@ -163,7 +163,15 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine
             for (int i = strlen(line); i >= 0; i--)
                if (line[i] == '\n' || line[i] == '\r')
                   line[i] = 0;
-            putenv(line);
+            // the file is self-documenting: skip comments, blanks,
+            // and anything that is not KEY=VALUE
+            char *setting = line;
+            while (*setting == ' ' || *setting == '\t')
+               ++setting;
+            if (*setting == '\0' || *setting == '#' || *setting == ';' ||
+                strchr(setting, '=') == NULL)
+               continue;
+            putenv(setting);
          }
       }
       fclose(file);
diff --git a/pack-dist.ps1 b/pack-dist.ps1
index 5233652..c18182a 100644
--- a/pack-dist.ps1
+++ b/pack-dist.ps1
@@ -73,14 +73,100 @@ if (Test-Path $openal) {
 
 # --- desktop configuration -------------------------------------------------
 Set-Content -Path "$dist\environ.ini" -Encoding ascii -Value @"
+# ============================================================================
+#  environ.ini - Red Planet 4.12 configuration
+# ============================================================================
+#  One KEY=VALUE per line, read at game start. Lines starting with # or ;
+#  are comments; anything without an = is ignored. Delete a line (or
+#  comment it out) to fall back to the built-in default.
+#
+#  Input bindings live in bindings.txt beside the exe (written with the
+#  full documented layout on first run; delete it to restore defaults).
+
+# ---- Core (the shipped configuration) --------------------------------------
+
+# Control stack. PAD;KEYBOARD = the virtual RIO (XInput controller +
+# keyboard, rebindable via bindings.txt). RIO;KEYBOARD = real serial
+# cockpit hardware. KEYBOARD = engine keyboard only (no virtual RIO).
 L4CONTROLS=PAD;KEYBOARD
+
+# Renderer selection argument and its config file. Leave as shipped.
 DPLARG=1
 L4DPLCFG=RPDPL.INI
+
+# Gauge (MFD/instrument) canvas: WIDTHxHEIGHTxDEPTH.
 L4GAUGE=640x480x16
+
+# Plasma display: SCREEN renders the pod's plasma glass in-window
+# (currently parked off-layout); hardware values drive real glass.
 L4PLASMA=SCREEN
+
+# 1 = the single-window cockpit: all seven displays composed on a
+# locked 1920x1080 canvas around the viewscreen.
 L4MFDSPLIT=1
+
+# Simulation/render frame rate.
 TARGETFPS=60
+
+# 1 = Steam networking (lobbies, FakeIP mesh). Needs the Steam client
+# running and steam_appid.txt beside the exe; without them the game
+# logs the reason and falls back to plain TCP. 0 = TCP only.
 RP412STEAM=1
+
+# ---- Optional ---------------------------------------------------------------
+
+# RGB keyboard lamp mirror (Windows Dynamic Lighting): keys bound to
+# lamp buttons glow with the panel, flash modes and all. Default on;
+# set 0 to disable.
+#RP412KEYLIGHT=0
+
+# Invert the stick on top of whatever bindings.txt produces: X, Y, XY.
+#L4PADFLIP=XY
+
+# Anti-aliasing samples (0 = off).
+#MULTISAMPLE=0
+
+# Particle budget.
+#MAXPARTICLES=8192
+
+# On-screen plasma glass pixel size and position (when re-homed).
+#L4PLASMASCALE=4
+#L4PLASMAPOS=0,0
+
+# Fixed random seed (repeatable runs).
+#RANDOM=12345
+
+# ---- LAN play without Steam -------------------------------------------------
+# Host a race over plain TCP: list the member pods' console channels
+# (members run: rpl4opt.exe -windowed -res 1920 1080 -net 1501).
+# HOSTADDR is this machine's LAN IP as members can reach it.
+#RP412HOSTPODS=192.168.1.20:1501,192.168.1.21:1501
+#RP412HOSTPORT=1501
+#RP412HOSTADDR=192.168.1.10
+
+# ---- Developer / testing ----------------------------------------------------
+
+# 1 arms the debug keys: Alt+W wireframe, Alt+V predator vision,
+# Alt+F frame dump, Alt+/ perf stats, Alt+E event-queue dump.
+# (Alt+Q, the mission abort, is always live.)
+#RP412DEVKEYS=1
+
+# Console race-length override in seconds (short test races).
+#L4CONSOLELEN=30
+
+# Steam transport loopback self-test at boot (logs PASS/FAIL).
+#RP412STEAMSELFTEST=1
+
+# ---- Arcade heritage (multi-monitor pods; not used on the desktop) ----------
+#PRIMGAUGE=1
+#SECGAUGE=2
+#MFDGAUGE=3
+#MFDGAUGE2=4
+#SPANDISABLE=1
+#L4EYES=1
+#L4INTERCOM=COM2
+#NOMODES=1
+#LOGSIZE=1000000
 "@
 
 Set-Content -Path "$dist\start-windowed.bat" -Encoding ascii -Value @"
@@ -121,9 +207,9 @@ at its left, and the lower MFDs flanking the portrait map. The red
 buttons around each MFD and the amber buttons beside the map are the
 pod's real button banks: click them with the mouse, and they light up
 as the game commands their lamps.
-environ.ini options: L4PADFLIP=XY inverts the stick axes, L4MFDSCALE=n
-sizes the MFD/map windows (percent, default 50), L4PLASMASCALE=n sets
-the plasma pixel size (default 4), L4PLASMAPOS=x,y places the plasma.
+environ.ini is self-documenting: every option ships in the file with
+a comment (Steam networking, keyboard lighting, stick inversion, LAN
+hosting, developer keys, and more).
 
 Known prototype notes: pods race untextured (the player1-8 skins come
 from the presets system, not shipped data), and text drawn on the plasma