Don't believe this. You only need to know very very little c++ or any language for that matter, to actually write a game. At the core all you need to know is how to make and manipulate variables. The first 20-30 pages of a c++ book is all you need to know really to make anything. Game development is not c++, common misconception in my opinion. Not enough material covers game development.
False.
The first 20-30 pages of a C++ book is all you need to know to write incredibly buggy, fragile, non-portable, unmaintainable, and largely undefined-behavior-reliant software.
Please do not do the community the disservice of perpetuating the myth that C++ can be used effectively without properly understanding a huge swath of its nuances and subtleties.