ccGo
The author Chun-Chung Chen (cjj@u.washington.edu) describes ccGo at https://ccdw.org/~cjj/prog/ccgo/ as an “IGS client written in C++”, a “project for sharpening my programming skill” with an emphasis on “elegant code”. The author also writes “To use it, you still need to be familiar with IGS text commands. ccgo only provides the UI in a need to be basis”. CcGo is supplied only for Linux, in source form for Debian Linux? and as a source RPM? for Fedora Linux?, most recently
https://ccdw.org/~cjj/files/srpms/ccgo-0.3.6.3-1.src.rpm. The most recent
Change Log entry is dated 2015-05-23.
These circumstances suggest that ccGo is not currently targeted at the casual Go player.