diff --git a/ArcFormats/ArcFormats.csproj b/ArcFormats/ArcFormats.csproj
index 97019ac2..dfd3ab19 100644
--- a/ArcFormats/ArcFormats.csproj
+++ b/ArcFormats/ArcFormats.csproj
@@ -107,6 +107,7 @@
     <Compile Include="ExeFile.cs" />
     <Compile Include="GameSystem\ArcCHR.cs" />
     <Compile Include="GameSystem\ArcCMP.cs" />
+    <Compile Include="GameSystem\ArcDAT.cs" />
     <Compile Include="GameSystem\ImageALP.cs" />
     <Compile Include="GameSystem\ImageBGD.cs" />
     <Compile Include="GameSystem\ImageCGD.cs" />
diff --git a/ArcFormats/GameSystem/ArcDAT.cs b/ArcFormats/GameSystem/ArcDAT.cs
new file mode 100644
index 00000000..c749cd09
--- /dev/null
+++ b/ArcFormats/GameSystem/ArcDAT.cs
@@ -0,0 +1,105 @@
+//! \file       ArcDAT.cs
+//! \date       Sat Jan 21 18:32:40 2017
+//! \brief      0verflow resource archive.
+//
+// Copyright (C) 2017 by morkt
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+//
+
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.Composition;
+using System.IO;
+using System.Text;
+
+namespace GameRes.Formats.GameSystem
+{
+    [Export(typeof(ArchiveFormat))]
+    public class DatOpener : ArchiveFormat
+    {
+        public override string         Tag { get { return "DAT/0verflow"; } }
+        public override string Description { get { return "0verflow resource archive"; } }
+        public override uint     Signature { get { return 0; } }
+        public override bool  IsHierarchic { get { return false; } }
+        public override bool      CanWrite { get { return false; } }
+
+        public override ArcFile TryOpen (ArcView file)
+        {
+            uint index_size = file.View.ReadUInt32 (0);
+            if (index_size <= 2 || index_size >= (uint.MaxValue >> 9))
+                return null;
+            index_size <<= 9;
+            if (index_size >= file.MaxOffset)
+                return null;
+            uint index_offset = 0x400;
+            long offset = (long)file.View.ReadUInt32 (index_offset+12) << 9;
+            if (offset != index_size)
+                return null;
+            var dir = new List<Entry>();
+            var entry_buf = file.View.ReadBytes (index_offset, 12);
+            while (!Array.TrueForAll (entry_buf, x => x == 0xFF))
+            {
+                index_offset += 0x10;
+                if (index_offset >= index_size)
+                    return null;
+                var name = RestoreName (entry_buf);
+                var entry = FormatCatalog.Instance.Create<Entry> (name);
+                file.View.Read (index_offset, entry_buf, 0, 12);
+                long next_offset = (long)file.View.ReadUInt32 (index_offset+12) << 9;
+                if (next_offset < offset || next_offset > file.MaxOffset)
+                    return null;
+                entry.Offset = offset;
+                entry.Size = (uint)(next_offset - offset);
+                dir.Add (entry);
+                offset = next_offset;
+            }
+            if (0 == dir.Count)
+                return null;
+            return new ArcFile (file, this, dir);
+        }
+
+        static string RestoreName (byte[] index)
+        {
+            var name_buf = new byte[0x10];
+            int dst = 0;
+            for (int i = 0; i < 12; i += 3)
+            {
+                int word = index[i] << 16 | index[i+1] << 8 | index[i+2];
+                name_buf[dst++] = (byte)(0x20 + ((word >> 18) & 0x3F));
+                name_buf[dst++] = (byte)(0x20 + ((word >> 12) & 0x3F));
+                name_buf[dst++] = (byte)(0x20 + ((word >> 6) & 0x3F));
+                name_buf[dst++] = (byte)(0x20 +  (word & 0x3F));
+            }
+            int name_end = Array.IndexOf<byte> (name_buf, 0x20, 0, 12);
+            if (0 == name_end)
+                throw new InvalidFormatException();
+            if (-1 == name_end)
+                name_end = 12;
+            var name = Encoding.ASCII.GetString (name_buf, 0, name_end);
+            int ext_end = Array.IndexOf<byte> (name_buf, 0x20, 12, 4);
+            if (12 == ext_end)
+                return name;
+            if (-1 == ext_end)
+                ext_end = 16;
+            var ext = Encoding.ASCII.GetString (name_buf, 12, ext_end-12);
+            return name + '.' + ext;
+        }
+    }
+}