Reducing confusion is what you need to do. If you want to teach C++, then say you are teaching C++ not C with some C++ features.
C is very different language compared to C++. Perfectly valid C code can be uncompileable C++ code.
One example is that in C, pointer types are weakly typed.
int* x = ...;
char* y = x; /* Valid C code but not C++ */
char* z = (char*)x; /* Both valid in C & C++ */
The weakly typed pointers are both useful and dangerous. They allow for polymorphism and subtyping.
If you teach people that this is C code, when they try a different compiler or OS, they will expect it to work as C code.
Be extremely clear with what you are teaching and try not to give misnomers or other false information.
If you are showing code from your game, that is fine but make sure you clearly show it is C++ and not C.
C is much simpler language compared to C++ and most people program different in one to the other.