/usr/lib/monodevelop/AddIns/ is in monodevelop-monogame 2.5.1+dfsg-3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/MonoDevelop.MonoGame.dll
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/icons/
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/icons/monogame-32.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/icons/monogame-project-16.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/icons/monogame-project-32.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameAndroidClass.xft.xml
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameAndroidProject.xpt.xml
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/AboutAssets.txt
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/AboutContent.txt
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/AboutResources.txt
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Activity1.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/AndroidAssemblyInfo.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/AssemblyInfo.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Game1.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Icon-hd.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Icon-ld.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Icon-md.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/MacGame.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/MacInfo.plist
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/MacMain.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Program.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Resource.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Splash.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/Styles.xml
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/iOSAssemblyInfo.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/iOSDefault.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/iOSGame.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/iOSGameThumbnail.png
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/iOSInfo.plist
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameApplication/iOSMain.cs
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameLinuxProject.xpt.xml
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameMacClass.xft.xml
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameMacProject.xpt.xml
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameWindowsProject.xpt.xml
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameiOSClass.xft.xml
/usr/lib/monodevelop/AddIns/MonoDevelop.MonoGame/templates/MonoGameiOSProject.xpt.xml