As a tip for anyone who had the compiler error when throwing int32 = int; into main.cpp.
Throw it into the .h file that needs that Type Alias. It will make sure that it goes into everything that is including that .h file.
In this case, its FBullCowGame.h that has the int32 definition. So the main.cpp and FBullCowGame.cpp files are both using the definition because it is checking the header file first.