diff --git a/ArcFormats/ArcFormats.csproj b/ArcFormats/ArcFormats.csproj
index 68906f1f..8e8b3622 100644
--- a/ArcFormats/ArcFormats.csproj
+++ b/ArcFormats/ArcFormats.csproj
@@ -110,6 +110,7 @@
     <Compile Include="CsWare\ImageBPC.cs" />
     <Compile Include="Cyberworks\ArcApp.cs" />
     <Compile Include="DirectDraw\DxtDecoder.cs" />
+    <Compile Include="elf\ArcAi5DAT.cs" />
     <Compile Include="ExHibit\ArcGRP.cs" />
     <Compile Include="Foster\ArcC24.cs" />
     <Compile Include="Foster\ArcFA2.cs" />
@@ -117,6 +118,7 @@
     <Compile Include="Foster\ImageC25.cs" />
     <Compile Include="GameSystem\ArcPureMail.cs" />
     <Compile Include="GameSystem\AudioADP4.cs" />
+    <Compile Include="ImageLZS.cs" />
     <Compile Include="ImagePIC.cs" />
     <Compile Include="ImagePNX.cs" />
     <Compile Include="ImagePSM.cs" />
diff --git a/ArcFormats/elf/ArcAi5DAT.cs b/ArcFormats/elf/ArcAi5DAT.cs
new file mode 100644
index 00000000..e4701e79
--- /dev/null
+++ b/ArcFormats/elf/ArcAi5DAT.cs
@@ -0,0 +1,95 @@
+//! \file       ArcAi5DAT.cs
+//! \date       2017 Dec 06
+//! \brief      Ai5Win engine 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.Collections.Generic;
+using System.ComponentModel.Composition;
+
+namespace GameRes.Formats.Elf
+{
+    [Export(typeof(ArchiveFormat))]
+    public class DatAI5Opener : ArchiveFormat
+    {
+        public override string         Tag { get { return "DAT/AI5WIN"; } }
+        public override string Description { get { return "AI5WIN engine 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 key = file.View.ReadUInt32 (4);
+            int count = (int)(file.View.ReadUInt32 (0) ^ key);
+            if (!IsSaneCount (count))
+                return null;
+            byte name_key = file.View.ReadByte (0x23);
+            var scheme = new ArcIndexScheme {
+                NameLength = 0x14, NameKey = name_key, SizeKey = key, OffsetKey = key
+            };
+            var reader = new Ai5DatIndexReader (file, count);
+            var dir = reader.Read (scheme);
+            if (dir != null)
+                return new ArcFile (file, this, dir);
+            return null;
+        }
+    }
+
+    internal class Ai5DatIndexReader : Ai5ArcIndexReader
+    {
+        public Ai5DatIndexReader (ArcView file, int count) : base (file, count)
+        {
+        }
+
+        new public List<Entry> Read (ArcIndexScheme scheme)
+        {
+            if (scheme.NameLength > m_name_buf.Length)
+                m_name_buf = new byte[scheme.NameLength];
+            m_dir.Clear();
+            int  index_offset = 8;
+            uint index_size = (uint)(m_count * (scheme.NameLength + 8));
+            if (index_size > m_file.View.Reserve (index_offset, index_size))
+                return null;
+            for (int i = 0; i < m_count; ++i)
+            {
+                uint size   = m_file.View.ReadUInt32 (index_offset)   ^ scheme.SizeKey;
+                uint offset = m_file.View.ReadUInt32 (index_offset+4) ^ scheme.OffsetKey;
+                if (offset < index_size+8)
+                    return null;
+                index_offset += 8;
+                m_file.View.Read (index_offset, m_name_buf, 0, (uint)scheme.NameLength);
+                string name = DecryptName (scheme);
+                if (null == name)
+                    return null;
+                index_offset += scheme.NameLength;
+                var entry = FormatCatalog.Instance.Create<Entry> (name);
+                entry.Offset = offset;
+                entry.Size   = size;
+                if (!entry.CheckPlacement (m_file.MaxOffset))
+                    return null;
+                m_dir.Add (entry);
+            }
+            return m_dir;
+        }
+    }
+}