diff --git a/docs/STEAM-3-MACHINE-TEST.md b/docs/STEAM-3-MACHINE-TEST.md
index 14d1551..69f6180 100644
--- a/docs/STEAM-3-MACHINE-TEST.md
+++ b/docs/STEAM-3-MACHINE-TEST.md
@@ -43,6 +43,29 @@ appid file is missing.
 6. Everyone lands back in the lobby room. A can launch again —
    different track, same lobby, no restarts.
 
+## Controllers: disable Steam Input (once per machine)
+
+Steam Input intercepts Xbox controllers for AppID 480 the moment the
+game initializes SteamAPI, hiding them from XInput entirely - the pad
+works everywhere else and is invisible only in-game (reproduced A/B on
+the dev box). Fix, either scope:
+
+- Per game: Steam Library -> Spacewar -> Properties -> Controller ->
+  Override for Spacewar: **Disable Steam Input**.
+- Global: Steam -> Settings -> Controller -> uncheck **Enable Steam
+  Input for Xbox controllers**.
+
+PadRIO re-probes every 3 seconds, so the pad hot-connects the moment
+Steam releases it - no restart needed. (Our own AppID will configure
+this server-side; test machines need the client setting.)
+
+## The abort key
+
+The ampersand key (Shift+7) is the arcade mission-abort. It ends YOUR
+mission on the spot - score banked, back to the lobby room. If the
+host presses it, the race ends for everyone (members return to the
+room too). Every "crash on keypress" so far has been this key.
+
 ## Notes and knowns
 
 - All pods use engine ports 1501/1502 by convention under Steam; the
diff --git a/pack-dist.ps1 b/pack-dist.ps1
index fd8a8b0..5a849c9 100644
--- a/pack-dist.ps1
+++ b/pack-dist.ps1
@@ -80,6 +80,7 @@ L4GAUGE=640x480x16
 L4PLASMA=SCREEN
 L4MFDSPLIT=1
 TARGETFPS=60
+RP412STEAM=1
 "@
 
 Set-Content -Path "$dist\start-windowed.bat" -Encoding ascii -Value @"