FakeNES is a highly portable, Open Source NES and Famicom emulator. It runs on all modern operating systems and has an actively maintained DOS port for enthusiasts. Support for phones and other mobile platforms is under development. The majority of the project is entirely original code released under the zlib/libpng license. Contributed and third-party code is included under GNU licenses.
The Fury² Game Creation System is a game development toolkit for the 32-bit Windows platform, designed to allow the creation of complex multimedia software and games with minimal unnecessary effort (i.e. reinventing the wheel.)
mmrts - A Real Time Strategy game engine made using Allegro. The initial game is a Tolkien-based world.
TurboSphere is an easy to learn and powerful JS based game engine.