There is already a complete lisp tool being implemented, aiming to take advantage of C++ libraries called Clasp. You can also take a look to some major Clisp/scheme libraries like biolisp (i think it's the name). I'd never make a group project in common lisp if this project do not involve either a finite-state machine or a DSL (rewriting a prolog interpretor in lisp is a breeze), and in this case, the language fits perfectly imho.