ZIG Game Engine
ZIG is a client-server game networking engine. The current main version is "2", and it was launched in July, 2007 with ZIG 2.0.0. It is free software, licensed under a BSD-like license.
From the standpoint of ZIG, the graphics renderer, the sound engine and the input handler are all extensions you must provide. You will be able to plug your Allegro, SDL, DirectX, OpenGL etc. stuff into ZIG with ease. ZIG is a cross-platform C/C++ library which depends only on HawkNL versions 1.7 beta 1 or later.
The ZIG project now has a Wiki - Look here for further information.
Go to the ZIG Wiki
Project at SourceForge: The sourceforge project page (bug and feature trackers, mailing list and project announcements).
Browse CVS: Browse the CVS repository to see what the code looks like right now!