Bigloo is an implementation of the Scheme programming language. It relies on an optimizing compiler from Scheme to C. Bigloo enables connections between Scheme code and C code. It proposes many extensions to Scheme such as a regular parser compiler, an lalr parser compiler, pattern matching, an object layer, etc.
Chicken is a Scheme compiler that translates most of R5RS Scheme into relatively portable C. It supports fully general tail-call recursion, first-class continuations, and has a very flexible and efficient interface to C and C++. Chicken implements several extensions to the Scheme language: lightweight threads, pattern matching macros, dynamic loading of compiled code, and various object-oriented paradigms, such as TinyCLOS, and others. The library system includes hundreds of convenient modules for practical use.
STklos is a free Scheme System conforming to R5RS. The implementation is based on an ad-hoc Virtual Machine. It can also be compiled as a library, so that one can easily embed it in an application. Its features include an efficient and powerful object system based on CLOS, a simple-to-use module system, implementation of the full tower of numbers defined in R5RS, and easy connection to the GTK+ toolkit. STklos is the successor of STk, a Scheme interpreter tightly connected to the Tk toolkit.
Thousand Parsec is a turn-based space empire building game, as well as a framework for creating a similar group of games, which are often called 4X games (eXplore, eXpand, eXploit, and eXterminate). Some examples of games from which Thousand Parsec draws ideas are Reach for the Stars, Stars!, VGA Planets, Master of Orion, and Galactic Civilizations. Unlike commercial alternatives, it is designed for long games supporting universes as large as your computer can handle. It allows a high degree of player customization, and features a flexible technology system where new technologies may be introduced mid-game.
Larceny is a simple and efficient implementation of the Scheme programming language. Created originally as a test vehicle for research on garbage collection and compiler optimizations, Larceny has grown into a major multi-platform system, and is one of the very few implementations that support all four de facto standards for Scheme: IEEE/ANSI, R5RS, ERR5RS, and the R6RS. Development of Larceny has been supported by NSF, Sun Microsystems, and Microsoft.
Halyard is a scriptable multimedia engine with support for video, audio, graphics, and user interaction. It currently runs on Windows, and has a preliminary Macintosh port. It is based on PLT Scheme, wxWidgets, and the Quake 2 Engine. It includes a rudimentary IDE based on Scintilla.