add -Dsilent=noupdate, to just start the app w/o any updates

core/src/main/java/com/threerings/getdown/data/SysProps.java

@@ -64,6 +64,14 @@ public class SysProps
      return System.getProperty("no_install") != null;
     }
 
+    /**
+     * If true, Getdown launches the app without updating. Usage:
+     * {@code -Dsilent=noupdate}.
+     */
+    public static boolean noUpdate() {
+        return "noupdate".equals(System.getProperty("silent"));
+    }
+
     /** If true, Getdown installs the app without ever bringing up a UI and then launches it.
       * Usage: {@code -Dsilent=launch}. */
     public static boolean launchInSilent () {

launcher/src/main/java/com/threerings/getdown/launcher/Getdown.java

@@ -54,6 +54,7 @@ public abstract class Getdown extends Thread
             // launch, start the application after installing. Otherwise, just install and exit.
             _silent = SysProps.silent();
             if (_silent) {
+                _noUpdate = SysProps.noUpdate();
                 _launchInSilent = SysProps.launchInSilent();
             }
             // If we're running in a headless environment and have not otherwise customized
@@ -306,6 +307,13 @@ public abstract class Getdown extends Thread
             _toInstallResources = new HashSet<>();
             _readyToInstall = false;
 
+            // directly start the app with the noupdate flag
+            if (_noUpdate) {
+                log.info("Launching without update!");
+                launch();
+                return;
+            }
+
             // setStep(Step.START);
             for (int ii = 0; ii < MAX_LOOPS; ii++) {
                 // make sure we have the desired version and that the metadata files are valid...
@@ -1041,6 +1049,7 @@ public abstract class Getdown extends Thread
 
     protected boolean _dead;
     protected boolean _silent;
+    protected boolean _noUpdate;
     protected boolean _launchInSilent;
     protected long _startup;