diff --git a/src/net/torvald/terrarum/App.java b/src/net/torvald/terrarum/App.java
index 8c05cbe5a..0bbfc104d 100644
--- a/src/net/torvald/terrarum/App.java
+++ b/src/net/torvald/terrarum/App.java
@@ -297,6 +297,7 @@ public class App implements ApplicationListener {
             // load configs
             getDefaultDirectory();
             createDirs();
+            initialiseConfig();
             readConfigJson();
             updateListOfSavegames();
 
@@ -988,7 +989,7 @@ public class App implements ApplicationListener {
 
     // CONFIG //
 
-    private static KVHashMap gameConfig = new KVHashMap();
+    public static KVHashMap gameConfig = new KVHashMap();
 
     private static void createConfigJson() throws IOException {
         File configFile = new File(configDir);
@@ -998,6 +999,15 @@ public class App implements ApplicationListener {
         }
     }
 
+    /**
+     * Reads DefaultConfig to populate the gameConfig
+     */
+    private static void initialiseConfig() {
+        for (Map.Entry<String, Object> entry : DefaultConfig.INSTANCE.getHashMap().entrySet()) {
+            gameConfig.set(entry.getKey(), entry.getValue());
+        }
+    }
+
     /**
      *
      * @return true on successful, false on failure.
diff --git a/src/net/torvald/terrarum/DefaultConfig.kt b/src/net/torvald/terrarum/DefaultConfig.kt
index 227d00696..999afa400 100644
--- a/src/net/torvald/terrarum/DefaultConfig.kt
+++ b/src/net/torvald/terrarum/DefaultConfig.kt
@@ -76,7 +76,7 @@ object DefaultConfig {
 
             "config_keyjump" to Input.Keys.SPACE,
 
-            "config_keyquickslots" to (Input.Keys.NUM_0..Input.Keys.NUM_9).toList(),
+            "config_keyquickslots" to (Input.Keys.NUM_0..Input.Keys.NUM_9).toList().toIntArray(),
 
             "config_mouseprimary" to Input.Buttons.LEFT, // left mouse
             "config_mousesecondary" to Input.Buttons.RIGHT, // right mouse
diff --git a/src/net/torvald/terrarum/KVHashMap.kt b/src/net/torvald/terrarum/KVHashMap.kt
index 6613d1a29..3a1f2a6d0 100644
--- a/src/net/torvald/terrarum/KVHashMap.kt
+++ b/src/net/torvald/terrarum/KVHashMap.kt
@@ -15,7 +15,7 @@ open class KVHashMap {
         hashMap = newMap
     }
 
-    protected var hashMap: HashMap<String, Any>
+    var hashMap: HashMap<String, Any>
 
     /**
      * Add key-value pair to the configuration table.
diff --git a/src/net/torvald/terrarum/modulebasegame/ui/UIRemoCon.kt b/src/net/torvald/terrarum/modulebasegame/ui/UIRemoCon.kt
index a8ee56711..3abc2bf8f 100644
--- a/src/net/torvald/terrarum/modulebasegame/ui/UIRemoCon.kt
+++ b/src/net/torvald/terrarum/modulebasegame/ui/UIRemoCon.kt
@@ -10,6 +10,7 @@ import net.torvald.terrarum.App.printdbgerr
 import net.torvald.terrarum.QNDTreeNode
 import net.torvald.terrarum.TitleScreen
 import net.torvald.terrarum.Yaml
+import net.torvald.terrarum.serialise.WriteConfig
 import net.torvald.terrarum.ui.UICanvas
 import net.torvald.terrarum.ui.UIItemTextButton
 import net.torvald.terrarum.ui.UIItemTextButtonList
@@ -92,7 +93,13 @@ open class UIRemoCon(val parent: TitleScreen, treeRepresentation: QNDTreeNode<St
                 //System.exit(0)
                 Gdx.app.exit()
             }
-            else if (it.labelText == "MENU_LABEL_RETURN") {
+            else if (it.labelText.startsWith("MENU_LABEL_RETURN")) {
+                val tag = it.labelText.substringAfter('+')
+
+                when (tag) {
+                    "WRITETOCONFIG" -> WriteConfig()
+                }
+
                 if (currentRemoConContents.parent != null) {
                     remoConTray.consume()
 
diff --git a/src/net/torvald/terrarum/modulebasegame/ui/UITitleLanguage.kt b/src/net/torvald/terrarum/modulebasegame/ui/UITitleLanguage.kt
index a2707552b..8700fff3d 100644
--- a/src/net/torvald/terrarum/modulebasegame/ui/UITitleLanguage.kt
+++ b/src/net/torvald/terrarum/modulebasegame/ui/UITitleLanguage.kt
@@ -70,10 +70,12 @@ class UITitleLanguage : UICanvas() {
         // attach listeners
         textArea1.selectionChangeListener = { _, newSelectionIndex ->
             App.GAME_LOCALE = localeList[newSelectionIndex]
+            App.setConfig("language", localeList[newSelectionIndex])
             textArea2.deselect()
         }
         textArea2.selectionChangeListener = { _, newSelectionIndex ->
             App.GAME_LOCALE = localeList[newSelectionIndex + localeFirstHalf.size]
+            App.setConfig("language", localeList[newSelectionIndex + localeFirstHalf.size])
             textArea1.deselect()
         }
 
diff --git a/src/net/torvald/terrarum/modulebasegame/ui/UITitleRemoConYaml.kt b/src/net/torvald/terrarum/modulebasegame/ui/UITitleRemoConYaml.kt
index c25c6c8f4..cf9a2327e 100644
--- a/src/net/torvald/terrarum/modulebasegame/ui/UITitleRemoConYaml.kt
+++ b/src/net/torvald/terrarum/modulebasegame/ui/UITitleRemoConYaml.kt
@@ -17,7 +17,7 @@ object UITitleRemoConYaml {
  - MENU_OPTIONS_CONTROLS : net.torvald.terrarum.modulebasegame.ui.UIKeyboardControlPanel
  - MENU_LABEL_LANGUAGE : net.torvald.terrarum.modulebasegame.ui.UITitleLanguage
  - MENU_MODULES : net.torvald.terrarum.ModOptionsHost
- - MENU_LABEL_RETURN
+ - MENU_LABEL_RETURN+WRITETOCONFIG
 - MENU_LABEL_CREDITS
  - MENU_LABEL_COPYRIGHT : net.torvald.terrarum.modulebasegame.ui.UITitleCredits
  - MENU_CREDIT_GPL_DNT : net.torvald.terrarum.modulebasegame.ui.UITitleGPL3
diff --git a/src/net/torvald/terrarum/serialise/WriteConfig.kt b/src/net/torvald/terrarum/serialise/WriteConfig.kt
new file mode 100644
index 000000000..3b2b595b6
--- /dev/null
+++ b/src/net/torvald/terrarum/serialise/WriteConfig.kt
@@ -0,0 +1,51 @@
+package net.torvald.terrarum.serialise
+
+import com.badlogic.gdx.utils.Json
+import com.badlogic.gdx.utils.JsonValue
+import com.badlogic.gdx.utils.JsonWriter
+import net.torvald.terrarum.App
+import net.torvald.terrarum.KVHashMap
+import net.torvald.terrarum.utils.JsonFetcher
+
+/**
+ * Created by minjaesong on 2021-09-19.
+ */
+object WriteConfig {
+
+    private val jsoner = Json(JsonWriter.OutputType.json)
+
+    init {
+        // KVHashMap
+        jsoner.setSerializer(KVHashMap::class.java, object : Json.Serializer<KVHashMap> {
+            override fun write(json: Json, obj: KVHashMap, knownType: Class<*>?) {
+                json.writeObjectStart()
+                obj.hashMap.toSortedMap().forEach { (k, v) ->
+                    json.writeValue(k, v)
+                }
+                json.writeObjectEnd()
+            }
+
+            override fun read(json: Json, jsonData: JsonValue, type: Class<*>?): KVHashMap {
+                val map = KVHashMap()
+                JsonFetcher.forEach(jsonData) { key, obj ->
+                    map[key] = json.readValue(null, obj)
+                }
+                return map
+            }
+        })
+
+    }
+
+    operator fun invoke() {
+        println("Writing config...")
+        App.gameConfig.hashMap.forEach { s, any ->
+            println("config $s = $any")
+        }
+
+
+        val writer = java.io.FileWriter(App.configDir, false)
+        writer.write(jsoner.prettyPrint(App.gameConfig))
+        writer.close()
+    }
+
+}
\ No newline at end of file
diff --git a/src/net/torvald/terrarum/utils/JsonFetcher.kt b/src/net/torvald/terrarum/utils/JsonFetcher.kt
index 872c930cf..b16166095 100644
--- a/src/net/torvald/terrarum/utils/JsonFetcher.kt
+++ b/src/net/torvald/terrarum/utils/JsonFetcher.kt
@@ -51,7 +51,7 @@ object JsonFetcher {
         var counter = 0
         var entry = map.child
         while (entry != null) {
-            action(entry.name ?: "(arrayindex $counter)", entry)
+            action(entry.name ?: "$counter", entry)
             entry = entry.next
             counter += 1
         }