Corrected Parceable Implementation. Wasn't aware that my code was not called. Had to force it to clear the app out of the memory.

app/src/main/java/org/secuso/privacyfriendlysudoku/controller/GameController.java

@@ -54,7 +54,7 @@ public class GameController implements IModelChangedListener, Parcelable {
     private int sectionWidth;
     private int usedHints = 0;
     private GameBoard gameBoard;
-    private int[] solution;
+    private int[] solution = new int[0];
     private GameType gameType;
     private GameDifficulty difficulty;
     private CellConflictList errorList = new CellConflictList();
@@ -699,6 +699,7 @@ public class GameController implements IModelChangedListener, Parcelable {
         out.writeInt(usedHints);
         out.writeInt(time);
 
+        out.writeInt(solution.length);
         out.writeIntArray(solution);
 
         out.writeInt(noteStatus ? 1 : 0);
@@ -738,18 +739,18 @@ public class GameController implements IModelChangedListener, Parcelable {
         usedHints = in.readInt();
         time = in.readInt();
 
+        solution = new int[in.readInt()];
         in.readIntArray(solution);
 
         noteStatus = in.readInt() == 1;
         notifiedOnSolvedListeners = in.readInt() == 1;
 
-        gameType = in.readParcelable(null);
+        gameType = in.readParcelable(GameType.class.getClassLoader());
-        difficulty = in.readParcelable(null);
+        difficulty = in.readParcelable(GameDifficulty.class.getClassLoader());
-        gameBoard = in.readParcelable(null);
+        gameBoard = in.readParcelable(GameBoard.class.getClassLoader());
-        undoRedoManager = in.readParcelable(null);
+        undoRedoManager = in.readParcelable(UndoRedoManager.class.getClassLoader());
 
         removeAllListeners();
-
     }
 
     public void removeAllListeners() {
@@ -758,4 +759,9 @@ public class GameController implements IModelChangedListener, Parcelable {
         hintListener = new LinkedList<>();
         timerListeners = new LinkedList<>();
     }
+
+    public void setContextAndSettings(Context applicationContext, SharedPreferences sharedPref) {
+        context = applicationContext;
+        setSettings(sharedPref);
+    }
 }

app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameBoard.java

@@ -290,7 +290,7 @@ public class GameBoard implements Cloneable, Parcelable {
         dest.writeInt(size);
 
         for(int i = 0; i < field.length; i++) {
-            dest.writeParcelableArray(field[i], 0);
+            dest.writeTypedArray(field[i], 0);
         }
 
     }
@@ -308,7 +308,7 @@ public class GameBoard implements Cloneable, Parcelable {
     /** recreate object from parcel */
     private GameBoard(Parcel in) {
         //private int id;
-        gameType = in.readParcelable(null);
+        gameType = in.readParcelable(GameType.class.getClassLoader());
         sectionHeight = in.readInt();
         sectionWidth = in.readInt();
         size = in.readInt();
@@ -316,8 +316,7 @@ public class GameBoard implements Cloneable, Parcelable {
         field = new GameCell[size][size];
 
         for(int i = 0; i < field.length; i++) {
-            // TODO: does this work?!
+            field[i] = in.createTypedArray(GameCell.CREATOR);
-            field[i] = (GameCell[]) in.readParcelableArray(null);
         }
 
         modelChangedListeners = new LinkedList<>();

app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameCell.java

@@ -213,10 +213,10 @@ public class GameCell implements Cloneable, Parcelable {
         dest.writeInt(row);
         dest.writeInt(col);
         dest.writeInt(value);
+        dest.writeInt(size);
         dest.writeInt(fixed ? 1 : 0);
         dest.writeInt(noteCount);
         dest.writeBooleanArray(notes);
-        dest.writeInt(size);
     }
 
     public static final Parcelable.Creator<GameCell> CREATOR
@@ -235,9 +235,10 @@ public class GameCell implements Cloneable, Parcelable {
         row = in.readInt();
         col = in.readInt();
         value = in.readInt();
+        size = in.readInt();
         fixed = in.readInt() == 1;
         noteCount = in.readInt();
+        notes = new boolean[size];
         in.readBooleanArray(notes);
-        size = in.readInt();
     }
 }

app/src/main/java/org/secuso/privacyfriendlysudoku/game/GameType.java

@@ -72,8 +72,7 @@ public enum GameType implements Parcelable{
         dest.writeInt(resIDImage);
     }
 
-    public static final Parcelable.Creator<GameType> CREATOR
+    public static final Parcelable.Creator<GameType> CREATOR = new Parcelable.Creator<GameType>() {
-            = new Parcelable.Creator<GameType>() {
         public GameType createFromParcel(Parcel in) {
             GameType g = GameType.values()[in.readInt()];
             g.resIDString = in.readInt();

app/src/main/java/org/secuso/privacyfriendlysudoku/ui/GameActivity.java

@@ -103,6 +103,7 @@ public class GameActivity extends AppCompatActivity implements NavigationView.On
             // in case we get the same object back
             // because parceling the Object does not always parcel it. Only if needed.
             gameController.removeAllListeners();
+            gameController.setContextAndSettings(getApplicationContext(), sharedPref);
             gameSolved = savedInstanceState.getInt("gameSolved") == 1;
         }