Syntopia is a free software synthesizer developed by Syntopia. Available format(s): VST for Windows.
Syntopia is a modular software synthesizer for use with a VST host. DX instrument and stand-alone editions are planned. Emphasis will be put on a functional graphical user interface, and a lot of freedom in the choice of synthesis algorithms/structure.
Syntopia is a C++ project for the Windows platform. Macintosh and Linux versions are a possibility but will require the participation of other programmers.
http://syntopia.sourceforge.net/