C++ build systems will be your main blocker, as they're languages in themselves. Autotools, CMake, configuring Visual Studio/etc.

Easy tasks:

- Challenge yourself by cloning projects reading their README and compiling/running them [1]

- Port projects to other platforms (e.g. Windows-only game examples to Linux/Mac/FreeBSD) [2]

Codebases I've studied [3]:

sdl/graphic widgets: openttd, aseprite, nanogui(-sdl)

runtime / abstraction: v8, node, protobuf, skia

templates / language integration: pybind11, boost-python

wrapping C: libsdl2pp (SDL2 wrapper)

small: tmux-mem-cpu-load, uMario_Jakowski

huge: blender

Architecture / theory: https://aosabook.org/en/wesnoth.html, https://aosabook.org/en/audacity.html, https://aosabook.org/en/cmake.html, https://www.aosabook.org/en/llvm.html

Books: Scott Meyers C++ books

[1] It's C, but to push myself to grok build systems I tried to port tmux's autotools build system to CMake: https://github.com/tony/tmux/compare/master...tony:cmake

[2] https://github.com/jakowskidev/uMario_Jakowski/pull/1

[3] https://github.com/tony/.dot-config/blob/5c59f46/.vcspull.ya...