Hi there rremedio,
The older versions of the chipmunk gem were cross compiled and published as binaries for Windows. As the only person that has touched maintenance on the chipmunk gem, I dropped the pre-built binaries for version 6. I'd love to add them back in, but I do not have time to do so. Feel free to file an issue here:
https://github.com/beoran/chipmunk If you or someone else wants to pick up that torch, let me know.
Also, I am the creator of chipmunk-ffi as well (built as a research project into FFI, not really great for games since FFI cannot use static inlines). If you file issues on github, I'll try to help with any errors.
https://github.com/shawn42/chipmunk-ffi