diff --git a/.idea/runConfigurations/Terrarum__no_prebuild_.xml b/.idea/runConfigurations/Terrarum__no_prebuild__release_mode_assets_.xml
similarity index 78%
rename from .idea/runConfigurations/Terrarum__no_prebuild_.xml
rename to .idea/runConfigurations/Terrarum__no_prebuild__release_mode_assets_.xml
index f90cc3abb..4127302de 100644
--- a/.idea/runConfigurations/Terrarum__no_prebuild_.xml
+++ b/.idea/runConfigurations/Terrarum__no_prebuild__release_mode_assets_.xml
@@ -1,7 +1,8 @@
 <component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Terrarum (no prebuild)" type="JarApplication">
+  <configuration default="false" name="Terrarum (no prebuild, release-mode assets)" type="JarApplication">
     <option name="JAR_PATH" value="$PROJECT_DIR$/out/TerrarumBuild.jar" />
     <option name="VM_PARAMETERS" value="-ea -Dswing.aatext=true -Dawt.useSystemAAFontSettings=lcd" />
+    <option name="PROGRAM_PARAMETERS" value="--assets buildapp/out/assets.tevd" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$" />
     <option name="ALTERNATIVE_JRE_PATH" value="17" />
     <module name="TerrarumBuild" />
diff --git a/src/net/torvald/terrarum/App.java b/src/net/torvald/terrarum/App.java
index 93ab0b7df..23fefab66 100644
--- a/src/net/torvald/terrarum/App.java
+++ b/src/net/torvald/terrarum/App.java
@@ -342,6 +342,14 @@ public class App implements ApplicationListener {
 
     public static boolean hasUpdate = true;
 
+    /**
+     * Path to a specific .tevd assets archive supplied via the --assets command-line argument.
+     * When non-null, this archive is used exclusively; the default ./assets.tevd and the
+     * local ./assets/ directory are both ignored.
+     */
+    @Nullable
+    public static String overrideAssetArchive = null;
+
     public static Screen getCurrentScreen() {
         return currentScreen;
     }
@@ -381,6 +389,17 @@ public class App implements ApplicationListener {
     }
 
     public static void main(String[] args) {
+//        System.out.println("Arguments: "+String.join(",", args));
+
+        // Parse command-line arguments before anything else
+        for (int i = 0; i < args.length; i++) {
+            if (args[i].equals("--assets") && i + 1 < args.length) {
+                overrideAssetArchive = args[i + 1];
+                System.out.println("Using custom assets: "+overrideAssetArchive);
+                i++;
+            }
+        }
+
         loadedTime_t = getTIME_T();
 
         updateBogoflops(100_000_000L);
@@ -441,7 +460,7 @@ public class App implements ApplicationListener {
             // load configs
             getDefaultDirectory();
             createDirs();
-            AssetCache.INSTANCE.init();
+            AssetCache.INSTANCE.init(overrideAssetArchive);
             initialiseConfig();
             readConfigJson();
 
diff --git a/src/net/torvald/terrarum/AssetCache.kt b/src/net/torvald/terrarum/AssetCache.kt
index 286f7641a..5447b0d2d 100644
--- a/src/net/torvald/terrarum/AssetCache.kt
+++ b/src/net/torvald/terrarum/AssetCache.kt
@@ -19,20 +19,30 @@ import java.io.RandomAccessFile
  */
 object AssetCache {
 
-    private val archivePath = File("./assets.tevd")
+    private val defaultArchivePath = File("./assets.tevd")
 
     /** Whether we're running from a distribution archive */
-    val isDistribution: Boolean get() = archivePath.exists()
+    val isDistribution: Boolean get() = dom != null
 
     private var dom: ClusteredFormatDOM? = null
 
     /**
      * Open the archive on startup. Call early, after defaultDir is set.
+     *
+     * @param overridePath When non-null, load this specific .tevd archive exclusively,
+     *                     ignoring both the default ./assets.tevd and the ./assets/ directory.
      */
-    fun init() {
-        if (isDistribution) {
-            println("[AssetCache] Distribution mode: opening ${archivePath.path}")
-            dom = ClusteredFormatDOM(RandomAccessFile(archivePath, "r"))
+    @JvmOverloads
+    fun init(overridePath: String? = null) {
+        if (overridePath != null) {
+            val f = File(overridePath)
+            if (!f.exists()) throw FileNotFoundException("Specified assets archive not found: $overridePath")
+            println("[AssetCache] Override archive: opening ${f.path}")
+            dom = ClusteredFormatDOM(RandomAccessFile(f, "r"))
+            println("[AssetCache] Override archive opened successfully")
+        } else if (defaultArchivePath.exists()) {
+            println("[AssetCache] Distribution mode: opening ${defaultArchivePath.path}")
+            dom = ClusteredFormatDOM(RandomAccessFile(defaultArchivePath, "r"))
             println("[AssetCache] Archive opened successfully")
         } else {
             println("[AssetCache] No archive found, using loose assets (development mode)")
@@ -41,13 +51,12 @@ object AssetCache {
 
     /**
      * Get a Clustfile for a path relative to the assets root.
+     *
+     * Note: nothing guarantees the file's actual existence!
      */
     fun getClustfile(relativePath: String): Clustfile {
         val path = if (relativePath.startsWith("/")) relativePath else "/$relativePath"
-        return Clustfile(dom!!, path).let {
-            if (!it.exists()) throw FileNotFoundException("Clustfile not exists: /$relativePath")
-            else it
-        }
+        return Clustfile(dom!!, path)
     }
 
     /**
diff --git a/src/net/torvald/terrarum/ClustfileHandle.kt b/src/net/torvald/terrarum/ClustfileHandle.kt
index 1102fe794..00a9d8328 100644
--- a/src/net/torvald/terrarum/ClustfileHandle.kt
+++ b/src/net/torvald/terrarum/ClustfileHandle.kt
@@ -1,11 +1,14 @@
 package net.torvald.terrarum
 
+import com.badlogic.gdx.Files
 import com.badlogic.gdx.files.FileHandle
+import com.badlogic.gdx.utils.GdxRuntimeException
 import net.torvald.terrarum.modulecomputers.virtualcomputer.tvd.archivers.Clustfile
 import net.torvald.terrarum.modulecomputers.virtualcomputer.tvd.archivers.ClustfileInputStream
 import java.io.File
 import java.io.InputStream
 
+
 /**
  * A GDX FileHandle backed by a Clustfile from TerranVirtualDisk.
  * Allows transparent asset loading from .tevd archives using all standard GDX APIs.
@@ -30,6 +33,10 @@ class ClustfileHandle(private val clustfile: Clustfile) : FileHandle() {
 
     override fun path(): String = clustfile.path
 
+    init {
+        type = Files.FileType.Internal // just a dummy value
+    }
+
     override fun extension(): String {
         val n = name()
         val dotIndex = n.lastIndexOf('.')
@@ -62,5 +69,12 @@ class ClustfileHandle(private val clustfile: Clustfile) : FileHandle() {
         return File(clustfile.path)
     }
 
+    override fun sibling(name: String?): FileHandle {
+        if (name == null) throw GdxRuntimeException("Sibling name must not be null.")
+        val parentPath = clustfile.parent ?: throw GdxRuntimeException("Cannot get the sibling of the root.")
+        val siblingPath = if (parentPath.endsWith("/")) "$parentPath$name" else "$parentPath/$name"
+        return ClustfileHandle(Clustfile(clustfile.DOM, siblingPath))
+    }
+
     override fun toString(): String = clustfile.path
 }
diff --git a/src/net/torvald/terrarum/ModMgr.kt b/src/net/torvald/terrarum/ModMgr.kt
index d0349b9f1..4dd843ea2 100644
--- a/src/net/torvald/terrarum/ModMgr.kt
+++ b/src/net/torvald/terrarum/ModMgr.kt
@@ -340,9 +340,7 @@ object ModMgr {
                             }
                         }
                         catch (e: Throwable) {
-                            printdbgerr(this, "Module failed to load, skipping: $moduleName")
-                            printdbgerr(this, "\t$e")
-                            print(App.csiR); e.printStackTrace(System.out); print(App.csi0)
+                            printdbgerr(this, "Module failed to load, skipping: $moduleName\nstacktrace:\n${e.stackTraceToString()}")
 
                             logError(LoadErrorType.YOUR_FAULT, moduleName, e)
 
@@ -370,7 +368,7 @@ object ModMgr {
                     printmsg(this, "Module processed: $moduleName")
                 }
                 catch (noSuchModule: FileNotFoundException) {
-                    printmsgerr(this, "No such module, skipping: $moduleName")
+                    printmsgerr(this, "No such module, skipping: $moduleName\nstacktrace:\n${noSuchModule.stackTraceToString()}")
 
                     logError(LoadErrorType.NOT_EVEN_THERE, moduleName, noSuchModule)
 
@@ -397,9 +395,7 @@ object ModMgr {
                     // TODO: Instead of skipping module with error, just display the error message onto the face?
 
 
-                    printmsgerr(this, "There was an error while loading module $moduleName")
-                    printmsgerr(this, "\t$e")
-                    print(App.csiR); e.printStackTrace(System.out); print(App.csi0)
+                    printmsgerr(this, "There was an error while loading module $moduleName\nstacktrace:\n${e.stackTraceToString()}")
 
                     logError(LoadErrorType.YOUR_FAULT, moduleName, e)
 
diff --git a/src/net/torvald/terrarum/Principii.java b/src/net/torvald/terrarum/Principii.java
index 04c69e6a7..6668fbf4f 100644
--- a/src/net/torvald/terrarum/Principii.java
+++ b/src/net/torvald/terrarum/Principii.java
@@ -17,9 +17,9 @@ import java.util.*;
  */
 public class Principii {
 
-    private static KVHashMap gameConfig = new KVHashMap();
+    private static final KVHashMap gameConfig = new KVHashMap();
 
-    private static String OSName = System.getProperty("os.name");
+    private static final String OSName = System.getProperty("os.name");
 
     private static String operationSystem;
     /** %appdata%/Terrarum, without trailing slash */
@@ -27,27 +27,29 @@ public class Principii {
     /** defaultDir + "/config.json" */
     private static String configDir;
 
+    private static final String GAME_NAME = TerrarumAppConfiguration.INSTANCE.getGAME_NAME_FOR_FILESYSTEM();
+
     public static void getDefaultDirRoot() {
         String OS = OSName.toUpperCase();
         if (OS.contains("WIN")) {
             operationSystem = "WINDOWS";
-            defaultDir = System.getenv("APPDATA") + "/Terrarum";
+            defaultDir = System.getenv("APPDATA") + "/" + GAME_NAME;
         }
         else if (OS.contains("OS X") || OS.contains("MACOS")) { // OpenJDK for mac will still report "Mac OS X" with version number "10.16", even on Big Sur and beyond
             operationSystem = "OSX";
-            defaultDir = System.getProperty("user.home") + "/Library/Application Support/Terrarum";
+            defaultDir = System.getProperty("user.home") + "/Library/Application Support/" + GAME_NAME;
         }
         else if (OS.contains("NUX") || OS.contains("NIX") || OS.contains("BSD")) {
             operationSystem = "LINUX";
-            defaultDir = System.getProperty("user.home") + "/.Terrarum";
+            defaultDir = System.getProperty("user.home") + "/." + GAME_NAME;
         }
         else if (OS.contains("SUNOS")) {
             operationSystem = "SOLARIS";
-            defaultDir = System.getProperty("user.home") + "/.Terrarum";
+            defaultDir = System.getProperty("user.home") + "/." + GAME_NAME;
         }
         else {
             operationSystem = "UNKNOWN";
-            defaultDir = System.getProperty("user.home") + "/.Terrarum";
+            defaultDir = System.getProperty("user.home") + "/." + GAME_NAME;
         }
     }
 
@@ -135,8 +137,9 @@ public class Principii {
         cmd0.add("-Xms1G");
         cmd0.add("-Xmx"+xmx+"G");
         cmd0.add("-cp");
-        cmd0.add("./out/TerrarumBuild.jar");
+        cmd0.add("./out/" + TerrarumAppConfiguration.JAR_NAME);
         cmd0.add(cp);
+        cmd0.addAll(List.of(args));
         var cmd = cmd0.stream().filter((it) -> !it.isBlank()).toList();
 
         System.out.println(cmd);
diff --git a/src/net/torvald/terrarum/TerrarumAppConfiguration.kt b/src/net/torvald/terrarum/TerrarumAppConfiguration.kt
index 67b0894ba..5e40b928d 100644
--- a/src/net/torvald/terrarum/TerrarumAppConfiguration.kt
+++ b/src/net/torvald/terrarum/TerrarumAppConfiguration.kt
@@ -17,6 +17,8 @@ object TerrarumAppConfiguration {
     // CONFIGURATION FOR THE APP ITSELF //
     //////////////////////////////////////
     const val GAME_NAME = "Terrarum"
+    const val JAR_NAME = "TerrarumBuild.jar" // must match what's on the buildapp scripts
+    val GAME_NAME_FOR_FILESYSTEM = GAME_NAME.replace(' ', '_')
     const val COPYRIGHT_DATE_NAME = "© 2013-2026 CuriousToꝛvald (minjaesong)"
     val COPYRIGHT_LICENSE: String; get() = Lang["COPYRIGHT_GNU_GPL_3"]
     const val COPYRIGHT_LICENSE_ENGLISH = "Distributed under GNU GPL 3"
@@ -38,7 +40,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 # Modules are loaded from top to bottom.
 # Name of the module corresponds with the name of the directory the module is stored in,
 # typically under:
-#    1. assets/mods of the installation path (the modules comes with the release of the game)
+#    1. assets.tevd/mods of the installation path (the modules comes with the release of the game)
 #    2. %APPDATA%/Modules (the modules installed by the user)
 #    where %APPDATA% is:
 #        Windows -- C:\Users\<username>\AppData\Roaming\Terrarum