Stars
Multi-purpose editor for ROM hacking DS and GBA Castlevania games
Managed Windows API (http://mwinapi.sourceforge.net/)
XNAFileDialog - Portable File Dialog for XNA Games
Some datamining stuff for The Legend of Zelda: Breath of the Wild
A simple WAD extraction command line tool for Doom-engine mods
Partial Telefang disassembly and English translation (on the patch branch)
Community effort to maintain and improve Jedi Academy (SP & MP) + Jedi Outcast (SP only) released by Raven Software
OpenRW "Open ReWrite" is an un-official open source recreation of the classic Grand Theft Auto III game executable
Source code for my Open Source GBA Pokémon Game Engine
An open source flash player implementation
XboxHLE is an experimental high-level Microsoft Original Xbox Emulator. At this time, it can only run very few homebrew samples.
espes / xqemu
Forked from qemu/qemuExperimental emulator for the original Xbox
An open source version of a game engine developed by Croteam for the classic Serious Sam games.
DarkFO, a post-nuclear RPG remake (of Fallout 2)
fonline-open-source is an open source implementation of the Fallout Online
Incomplete Star Trek Voyager: Elite Force (MP) game code remake for Spearmint.
The project which restores halo 2 PC multiplayer online through the "Network" area, while also adding new features such as GunGame and more to come.
GZDoom-GPL is a GPL-compliant fork of GZDoom.
A free, single-player roguelike dungeon exploration game
FNA - Accuracy-focused XNA4 reimplementation for open platforms
This aims to become a base for standalone games based on the free Doom3 engine