A new version of the open source VM VirtualBox has been released. VirtualBox is available for different operating systems like Windows, Linux, Solaris and Mac OS.
GZDoom is an enhanced port based on the sources of Doom for Windows.
ResidualVM is a virtual machine for the engines GrimE and Sprint. ResidualVM supports Grim Fandango, Escape from Monkey Island (MI4) and Myst III: Exile
Devilution - Diablo devolved is a reverse engineered source project of the classic game from 1996.
A new version of the Doom source port Doom Legacy has been released.
OpenMW is an open-source engine for the game The Elder Scrolls 3: Morrowind.
Yamagi Quake II is an enhanced client for Quake II.
A new version of the Doom, Heretic and Hexen source port Doomsday Engine has been released. This was half a year ago, but better late then never. ;)
A new version of the popular virtual machine for classic adventures ScummVM has been released a few days ago.
FreeOrion is an open source project that aims to provide a free and platform-independent game in the tradition of the Master of Orion games (released under the GPL) (Changelog).