diff --git a/playback/Playback/MessageReader.cs b/playback/Playback/MessageReader.cs
index 9f983da..f4badfe 100644
--- a/playback/Playback/MessageReader.cs
+++ b/playback/Playback/MessageReader.cs
@@ -45,11 +45,6 @@ namespace Playback
                 fs.Read(bt, 0, bt.Length);
                 for (int i = 0; i < prefixLen; ++i)
                 {
-                    if (i == 2)
-                    {
-                        if (bt[i] == 0)  // 为了做一个兼容，0和5均视为5
-                            continue;
-                    }
                     if (bt[i] != PlayBackConstant.Prefix[i]) throw new FileFormatNotLegalException(fileName);
                 }
 
diff --git a/playback/Playback/Playback.csproj b/playback/Playback/Playback.csproj
index 132c02c..70e6d49 100644
--- a/playback/Playback/Playback.csproj
+++ b/playback/Playback/Playback.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFrameworks>net6.0;netstandard2.1</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
diff --git a/playback/Playback/PlaybackConstant.cs b/playback/Playback/PlaybackConstant.cs
index 73de67f..fae4668 100644
--- a/playback/Playback/PlaybackConstant.cs
+++ b/playback/Playback/PlaybackConstant.cs
@@ -3,6 +3,6 @@ namespace Playback
     public static class PlayBackConstant
     {
         public static string ExtendedName = ".thuaipb";
-        public static byte[] Prefix = { (byte)'P', (byte)'B', 0, 0 };   // 文件前缀，用于标识文件类型，版本号为5
+        public static byte[] Prefix = { (byte)'P', (byte)'B', 5, 0 };   // 文件前缀，用于标识文件类型，版本号为6
     }
 }
diff --git a/playback/PlaybackForUnity/MessageReaderForUnity.cs b/playback/PlaybackForUnity/MessageReaderForUnity.cs
deleted file mode 100644
index 75f96e8..0000000
--- a/playback/PlaybackForUnity/MessageReaderForUnity.cs
+++ /dev/null
@@ -1,137 +0,0 @@
-using Communication.Proto;
-using Google.Protobuf;
-using System;
-using System.IO;
-using System.IO.Compression;
-
-namespace Playback
-{
-	public class FileFormatNotLegalException : Exception
-	{
-		private readonly string fileName;
-		public FileFormatNotLegalException(string fileName)
-		{
-			this.fileName = fileName;
-		}
-		public override string Message => $"The file: " + this.fileName + " is not a legal playback file for THUAI6.";
-	}
-
-	public class MessageReader : IDisposable
-	{
-		private FileStream fs;
-		private CodedInputStream cos;
-		private GZipStream gzs;
-		private byte[] buffer;
-		public bool Finished { get; private set; } = false;
-
-		public readonly uint teamCount;
-		public readonly uint playerCount;
-
-		const int bufferMaxSize = 1024 * 1024;       // 1M
-
-		public MessageReader(string fileName)
-		{
-			if (!fileName.EndsWith(PlaybackConstantForUnity.ExtendedName))
-			{
-				fileName += PlaybackConstantForUnity.ExtendedName;
-			}
-
-			fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
-
-			try
-			{
-				var prefixLen = PlaybackConstantForUnity.Prefix.Length;
-				byte[] bt = new byte[prefixLen + sizeof(UInt32) * 2];
-				fs.Read(bt, 0, bt.Length);
-				for (int i = 0; i < prefixLen; ++i)
-				{
-					if (i == 2)
-					{
-						if (bt[i] == 0) 
-							continue;
-					}
-					if (bt[i] != PlaybackConstantForUnity.Prefix[i]) throw new FileFormatNotLegalException(fileName);
-				}
-
-				teamCount = BitConverter.ToUInt32(bt, prefixLen);
-				playerCount = BitConverter.ToUInt32(bt, prefixLen + sizeof(UInt32));
-			}
-			catch
-			{
-				throw new FileFormatNotLegalException(fileName);
-			}
-
-			gzs = new GZipStream(fs, CompressionMode.Decompress);
-			var tmpBuffer = new byte[bufferMaxSize];
-			var bufferSize = gzs.Read(tmpBuffer, 0, tmpBuffer.Length);
-			if (bufferSize == 0)
-			{
-				buffer = tmpBuffer;
-				Finished = true;
-			}
-			else if (bufferSize != bufferMaxSize)       // 不留空位，防止 CodedInputStream 获取信息错误
-			{
-				if (bufferSize == 0)
-				{
-					Finished = true;
-				}
-				buffer = new byte[bufferSize];
-				Array.Copy(tmpBuffer, buffer, bufferSize);
-			}
-			else
-			{
-				buffer = tmpBuffer;
-			}
-			cos = new CodedInputStream(buffer);
-		}
-
-		public MessageToClient ReadOne()
-		{
-		beginRead:
-			if (Finished) return null;
-			var pos = cos.Position;
-			try
-			{
-				MessageToClient msg = new MessageToClient();
-				cos.ReadMessage(msg);
-				return msg;
-			}
-			catch (InvalidProtocolBufferException)
-			{
-				var leftByte = buffer.Length - pos;     // 上次读取剩余的字节
-				for (int i = 0; i < leftByte; ++i)
-				{
-					buffer[i] = buffer[pos + i];
-				}
-				var bufferSize = gzs.Read(buffer, (int)leftByte, (int)(buffer.Length - leftByte)) + leftByte;
-				if (bufferSize == leftByte)
-				{
-					Finished = true;
-					return null;
-				}
-				if (bufferSize != buffer.Length)        // 不留空位，防止 CodedInputStream 获取信息错误
-				{
-					var tmpBuffer = new byte[bufferSize];
-					Array.Copy(buffer, tmpBuffer, bufferSize);
-					buffer = tmpBuffer;
-				}
-				cos = new CodedInputStream(buffer);
-				goto beginRead;
-			}
-		}
-
-		public void Dispose()
-		{
-			Finished = true;
-			if (fs.CanRead)
-			{
-				fs.Close();
-			}
-		}
-
-		~MessageReader()
-		{
-			Dispose();
-		}
-	}
-}
diff --git a/playback/PlaybackForUnity/PlaybackConstantForUnity.cs b/playback/PlaybackForUnity/PlaybackConstantForUnity.cs
deleted file mode 100644
index b4d1701..0000000
--- a/playback/PlaybackForUnity/PlaybackConstantForUnity.cs
+++ /dev/null
@@ -1,8 +0,0 @@
-namespace Playback
-{
-    public static class PlaybackConstantForUnity
-    {
-        public static string ExtendedName = ".thuaipb";
-        public static byte[] Prefix = { (byte)'P', (byte)'B', 0, 0 };   // 文件前缀，用于标识文件类型
-    }
-}
diff --git a/playback/PlaybackForUnity/PlaybackForUnity.csproj b/playback/PlaybackForUnity/PlaybackForUnity.csproj
deleted file mode 100644
index 9581f42..0000000
--- a/playback/PlaybackForUnity/PlaybackForUnity.csproj
+++ /dev/null
@@ -1,8 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
-  </PropertyGroup>
-
-
-</Project>