My GSoD task was to improve the Doxygen-generated documentation of ScummVM in terms of its structure, completeness, language, style, coherence, and overall usability.
Completed tasks
This is my final GSoD deliverable:
https://doxygen.scummvm.org/modules.html
To be clear, I have not created all of this from scratch. Doxygen comments have existed in ScummVM header files since forever, as they are a standard way of documenting C and C++ code, so that it can be used and understood by other developers (which is of huge importance especially in an open-source project).