Made a 2nd "_xna" .csproj file for the C# runtimes. This is unavoidable, as microsoft is ass-backwards. The proper solution would be to add an "XNA" configuration (or even better, "XNA-XBOX" and "XNA-Windows" configuration), but Microsoft requires that any project referenced by XNA also import XNA, even if the base project doesn't depend on it.

Removed a lot of unneccessary stuff from the normal spine-csharp.csproj file, as no one else has Ultimate Edition and they were not configured properly.
Changed the XNA solution to point to the _xna csproj.

spine-csharp/spine-csharp.csproj

@@ -30,14 +30,8 @@
     <NoStdLib>true</NoStdLib>
     <DebugType>full</DebugType>
     <PlatformTarget>AnyCPU</PlatformTarget>
-    <CodeAnalysisLogFile>bin\x86\Debug\spine-csharp.dll.CodeAnalysisLog.xml</CodeAnalysisLogFile>
-    <CodeAnalysisUseTypeNameInSuppression>true</CodeAnalysisUseTypeNameInSuppression>
-    <CodeAnalysisModuleSuppressionsFile>GlobalSuppressions.cs</CodeAnalysisModuleSuppressionsFile>
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <ErrorReport>prompt</ErrorReport>
-    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
-    <CodeAnalysisRuleSetDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\\Rule Sets</CodeAnalysisRuleSetDirectories>
-    <CodeAnalysisRuleDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop\\Rules</CodeAnalysisRuleDirectories>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|AnyCPU'">
     <OutputPath>bin\Release\</OutputPath>
@@ -46,15 +40,8 @@
     <NoStdLib>true</NoStdLib>
     <DebugType>pdbonly</DebugType>
     <PlatformTarget>AnyCPU</PlatformTarget>
-    <CodeAnalysisLogFile>bin\x86\Release\spine-csharp.dll.CodeAnalysisLog.xml</CodeAnalysisLogFile>
-    <CodeAnalysisUseTypeNameInSuppression>true</CodeAnalysisUseTypeNameInSuppression>
-    <CodeAnalysisModuleSuppressionsFile>GlobalSuppressions.cs</CodeAnalysisModuleSuppressionsFile>
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <ErrorReport>prompt</ErrorReport>
-    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
-    <CodeAnalysisRuleSetDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\\Rule Sets</CodeAnalysisRuleSetDirectories>
-    <CodeAnalysisRuleDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop\\Rules</CodeAnalysisRuleDirectories>
-    <CodeAnalysisIgnoreBuiltInRules>true</CodeAnalysisIgnoreBuiltInRules>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="mscorlib" />

spine-csharp/spine-csharp_xna.csproj

@@ -0,0 +1,85 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <ProjectGuid>{94144E22-2431-4A8F-AC04-DEC22F7EDD8F}</ProjectGuid>
+    <ProductVersion>9.0.21022</ProductVersion>
+    <SchemaVersion>2.0</SchemaVersion>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>Spine</RootNamespace>
+    <AssemblyName>spine-csharp_xna</AssemblyName>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
+    <TargetFrameworkProfile>
+    </TargetFrameworkProfile>
+    <XnaFrameworkVersion>v4.0</XnaFrameworkVersion>
+    <XnaPlatform>Windows</XnaPlatform>
+    <XnaProfile>HiDef</XnaProfile>
+    <XnaCrossPlatformGroupID>99dfd52d-8beb-4e5c-a68b-365be39e8064</XnaCrossPlatformGroupID>
+    <XnaOutputType>Library</XnaOutputType>
+    <FileUpgradeFlags>
+    </FileUpgradeFlags>
+    <OldToolsVersion>3.5</OldToolsVersion>
+    <UpgradeBackupLocation />
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|AnyCPU'">
+    <DebugSymbols>true</DebugSymbols>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE;WINDOWS</DefineConstants>
+    <NoStdLib>true</NoStdLib>
+    <DebugType>full</DebugType>
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|AnyCPU'">
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE;WINDOWS</DefineConstants>
+    <Optimize>true</Optimize>
+    <NoStdLib>true</NoStdLib>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="mscorlib" />
+    <Reference Include="System" />
+    <Reference Include="System.Core">
+      <RequiredTargetFramework>4.0</RequiredTargetFramework>
+    </Reference>
+    <Reference Include="System.Net" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="src\Animation.cs" />
+    <Compile Include="src\AnimationStateData.cs" />
+    <Compile Include="src\Atlas.cs" />
+    <Compile Include="src\Attachments\AttachmentLoader.cs" />
+    <Compile Include="src\Attachments\AtlasAttachmentLoader.cs" />
+    <Compile Include="src\Attachments\Attachment.cs" />
+    <Compile Include="src\Attachments\AttachmentType.cs" />
+    <Compile Include="src\Attachments\RegionAttachment.cs" />
+    <Compile Include="src\Bone.cs" />
+    <Compile Include="src\BoneData.cs" />
+    <Compile Include="src\AnimationState.cs" />
+    <Compile Include="src\Json.cs" />
+    <Compile Include="src\Skeleton.cs" />
+    <Compile Include="src\SkeletonData.cs" />
+    <Compile Include="src\SkeletonJson.cs" />
+    <Compile Include="src\Skin.cs" />
+    <Compile Include="src\Slot.cs" />
+    <Compile Include="src\SlotData.cs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
+  <Import Project="$(MSBuildExtensionsPath)\Microsoft\XNA Game Studio\Microsoft.Xna.GameStudio.targets" Condition="exists('$(MSBuildExtensionsPath)\Microsoft\XNA Game Studio\Microsoft.Xna.GameStudio.targets')" />
+  <!--
+      To modify your build process, add your task inside one of the targets below and uncomment it.
+      Other similar extension points exist, see Microsoft.Common.targets.
+      <Target Name="BeforeBuild">
+      </Target>
+      <Target Name="AfterBuild">
+      </Target>
+    -->
+</Project>

spine-xna/spine-xna.sln

@@ -5,7 +5,7 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "spine-xna", "spine-xna.cspr
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "spine-xna-example", "example\spine-xna-example.csproj", "{29CC4385-294A-4885-A3E8-FD4825E0CFDD}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "spine-csharp", "..\spine-csharp\spine-csharp.csproj", "{94144E22-2431-4A8F-AC04-DEC22F7EDD8F}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "spine-csharp_xna", "..\spine-csharp\spine-csharp_xna.csproj", "{94144E22-2431-4A8F-AC04-DEC22F7EDD8F}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution