exDreamDuck 

SlimDX is a free open source framework that enables developers to easily build DirectX applications using .NET technologies such as C#, VB.NET, and IronPython.

The Open Toolkit Library (OpenTK) with OpenAL multimedia support

Spine is a 2D skeletal animation tool for game development and other animation projects.

Farseer Physics Engine is a collision detection system with realistic physics responses.

ToyMP3 is a simple mp3 (Mpeg1-Layer3) decoder implemented in C#

VLC is a free and open source cross-platform multimedia player and framework that plays most multimedia files as well as DVD, Audio CD, VCD, and various streaming protocols. This is a helper library to support Vlc videos as textures to be used in graphical engines like the Delta Engine.

Pencil.Gaming library to access the native GLFW3 framework

Jitter Physics is a fast and lightweight physics engine written in C#.

Provides simple C# SyntaxHighlight textbox support in WPF with C# parsing

Smart Device Connectivity APIs enable developers to take advantage of some core connectivity features in their applications.

Pencil.Gaming library to access the native GLFW2 framework

Farseer Physics Engine is a collision detection system with realistic physics responses.