And a "port" to Windows: https://github.com/fabriceleal/ecl-win-vs11-example.
Also a tiny non-working "game-engine" that uses SDL1.2 (while not working, may have more examples): https://github.com/rjmacready/pico-gmengine
I think guile it's better for language embedding. Anyway if you prefer lisp (to use an asdf package for example) maybe it's better sbcl with ffi.
Chicken scheme it's also nice and very portable.
MKCL, fork of ECL Last version MKCL 1.1.9: 2014/07/04 http://common-lisp.net/project/mkcl/
You can't easily embed SBCL inside a C program, can you?
Gambit and Bigloo are also full-featured Scheme variants that compile to C and are therefore easy to embed in a C program.
And a "port" to Windows: https://github.com/fabriceleal/ecl-win-vs11-example.
Also a tiny non-working "game-engine" that uses SDL1.2 (while not working, may have more examples): https://github.com/rjmacready/pico-gmengine