Hello!
Compared to Heavy, your ChucK code is compiled at runtime, so you can even assemble ChucK scripts on the fly with string manipulation while your game is currently running.
If you're looking to embed ChucK in another program, you will want to use the ChucK class in the core/chuck.cpp file as the interface. You will need to include all of the core/ files and none of the host/ files. The changes we made to ChucK involved separating its core logic (most of it) from its host -- command line and RtAudio interface, as well as reducing its dependencies on global variables so that multiple ChucK VM instances can coexist.
Then, there's also the new "global" variables in ChucK. If you add the global keyword to a variable, it's accessible by name across the entire VM (ChucK instance), and can also be set and gotten from outside ChucK (e.g. from Unity).
~Jack