diff --git a/ArcFormats/MangaGamer/ArcMGPK.cs b/ArcFormats/MangaGamer/ArcMGPK.cs
index 0cc08e1f..537f0eec 100644
--- a/ArcFormats/MangaGamer/ArcMGPK.cs
+++ b/ArcFormats/MangaGamer/ArcMGPK.cs
@@ -71,8 +71,9 @@ namespace GameRes.Formats.Mg
 
         public override ArcFile TryOpen (ArcView file)
         {
+            int version = file.View.ReadInt32 (4);
             int count = file.View.ReadInt32 (8);
-            if (count > 0xFFFFF)
+            if (version < 1 || !IsSaneCount (count))
                 return null;
             long cur_offset = 0x0C;
             var dir = new List<Entry> (count);
@@ -81,7 +82,7 @@ namespace GameRes.Formats.Mg
             {
                 uint name_length = file.View.ReadByte (cur_offset);
                 string name = file.View.ReadString (cur_offset+1, name_length, Encoding.UTF8);
-                var entry = FormatCatalog.Instance.Create<Entry> (name);
+                var entry = Create<Entry> (name);
                 entry.Offset = file.View.ReadUInt32 (cur_offset+0x20);
                 entry.Size = file.View.ReadUInt32 (cur_offset+0x24);
                 if (!entry.CheckPlacement (file.MaxOffset))
@@ -92,9 +93,9 @@ namespace GameRes.Formats.Mg
             }
             if (has_encrypted && KnownKeys.Count > 0)
             {
-                var options = Query<MgOptions> (arcStrings.ArcEncryptedNotice);
-                if (options.Key != null)
-                    return new MgArchive (file, this, dir, options.Key);
+                var key = QueryKey (file.Name);
+                if (key != null)
+                    return new MgArchive (file, this, dir, key);
             }
             return new ArcFile (file, this, dir);
         }
@@ -109,14 +110,14 @@ namespace GameRes.Formats.Mg
             {
                 byte[] data = new byte[entry.Size];
                 input.Read (data, 0, data.Length);
-                data = DecryptBlock (data, mgarc.Key);
+                DecryptData (data, mgarc.Key);
                 if (entry.Name.HasExtension ("txt"))
                     return DecompressStream (data);
                 return new BinMemoryStream (data, entry.Name);
             }
         }
 
-        private byte[] DecryptBlock (byte[] input, byte[] key)
+        protected virtual void DecryptData (byte[] input, byte[] key)
         {
             key = (byte[])key.Clone();
             for (int i = 0; i < input.Length; i++)
@@ -124,14 +125,13 @@ namespace GameRes.Formats.Mg
                 input[i] ^= key[i % key.Length];
                 key[i % key.Length] += 27;
             }
-            return input;
         }
 
-        private Stream DecompressStream (byte[] input)
+        internal Stream DecompressStream (byte[] input)
         {
             byte[] output = new byte[input.Length * 2];
             int output_size = lzf_decompress (input, ref output);
-            return new MemoryStream (output, 0, output_size);
+            return new BinMemoryStream (output, 0, output_size);
         }
 
         private static int lzf_decompress (byte[] input, ref byte[] output)
@@ -175,6 +175,12 @@ namespace GameRes.Formats.Mg
             return dst;
         }
 
+        internal byte[] QueryKey (string arc_name)
+        {
+            var options = Query<MgOptions> (arcStrings.ArcEncryptedNotice);
+            return options.Key;
+        }
+
         public override ResourceOptions GetDefaultOptions ()
         {
             return new MgOptions { Key = GetKey (Properties.Settings.Default.MGPKTitle) };
@@ -193,12 +199,64 @@ namespace GameRes.Formats.Mg
             return key;
         }
 
-        public static Dictionary<string, byte[]> KnownKeys = new Dictionary<string, byte[]>();
+        public static Dictionary<string, byte[]> KnownKeys { get { return DefaultScheme.KnownKeys; } }
+
+        static MgScheme DefaultScheme = new MgScheme { KnownKeys = new Dictionary<string, byte[]>() };
 
         public override ResourceScheme Scheme
         {
-            get { return new MgScheme { KnownKeys = KnownKeys }; }
-            set { KnownKeys = ((MgScheme)value).KnownKeys; }
+            get { return DefaultScheme; }
+            set { DefaultScheme = (MgScheme)value; }
         }
     }
+
+    [Export(typeof(ArchiveFormat))]
+    public class Mgpk0Opener : MgpkOpener
+    {
+        public override string         Tag { get { return "MGPK0"; } }
+        public override string Description { get { return "MG resource archive"; } }
+        public override uint     Signature { get { return 0x4B50474D; } } // MGPK
+        public override bool  IsHierarchic { get { return false; } }
+        public override bool      CanWrite { get { return false; } }
+
+        public override ArcFile TryOpen (ArcView file)
+        {
+            int version = file.View.ReadInt32 (4);
+            int count = file.View.ReadInt32 (8);
+            if (version != 0 || !IsSaneCount (count))
+                return null;
+            long cur_offset = 0x0C;
+            var dir = new List<Entry> (count);
+            bool has_encrypted = false;
+            for (int i = 0; i < count; ++i)
+            {
+                string name = file.View.ReadString (cur_offset, 0x20, Encoding.UTF8);
+                var entry = Create<Entry> (name);
+                entry.Offset = file.View.ReadUInt32 (cur_offset+0x20);
+                entry.Size = file.View.ReadUInt32 (cur_offset+0x2C);
+                if (!entry.CheckPlacement (file.MaxOffset))
+                    return null;
+                has_encrypted = has_encrypted || name.HasAnyOfExtensions ("png", "txt");
+                dir.Add (entry);
+                cur_offset += 0x30;
+            }
+            if (has_encrypted)
+            {
+                var key = QueryKey (file.Name);
+                if (key != null)
+                    return new MgArchive (file, this, dir, key);
+            }
+            return new ArcFile (file, this, dir);
+        }
+
+        protected override void DecryptData (byte[] input, byte[] key)
+        {
+            for (int i = 0; i < input.Length; i++)
+            {
+                input[i] ^= key[i % key.Length];
+            }
+        }
+
+        public override ResourceScheme Scheme { get; set; }
+    }
 }