xna topic
FNA
FNA - Accuracy-focused XNA4 reimplementation for open platforms
SimplexRpgEngine
Modular game engine built with MonoGame, with GMS2-like workflow and advanced level editor
HidGuardian
Windows kernel-mode driver for controlling access to various input devices.
XNAGameStudio
The Education library from the Xbox Live Indie games repository, valuable for MonoGame Developers for advanced samples
Xelmish
XNA + Elmish - 2D game development framework with F#
xna-cncnet-client
XNA / MonoGame based client for playing classic Command & Conquer games both online and offline with a CnCNet game spawner.
ultraviolet
The Ultraviolet Framework is a .NET game development framework written in C#.
dwarfcorp
An open-source 3D colony management game for PC, Mac and Linux
openrails
Open Rails: free train simulator that supports the world's largest range of digital content.
Pixel3D
2.5D pixel-based game engine built on XNA/FNA/MonoGame.