BattleTech MUX Client
C++ lightweight cross-platform game engine
Opengate is a Jumpgate remake
SDL based generic 2D game engine
Online War system for IL-2 Sturmovik and Iron Front in ArmA 2
Fast small FPS using JOGL and JOAL
General Purpose Engine for Graphic Adventures.
2D Open Source MMORPG
A cross-platform, multimedia interpreter for TADS adventure games.
KildClient is a powerful MUD client with a built-in Perl interpreter
0 A.D. is a free, open-source, cross-platform real-time strategy game.