MonoGame.Samples/RockRain/Core/RockRain.Core.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <AssemblyName>RockRain.Core</AssemblyName>
    <RootNamespace>RockRain</RootNamespace>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="MonoGame.Framework.DesktopGL" Version="3.8.*" PrivateAssets="all" />
  </ItemGroup>


</Project>