I have my expertise in C++ and also in STL as well as SFML. If you want to have an GUI 2d interface then in that case you want a freelancer to use SFML. STL is a Standard Template Library which in C++ is used for storing data, the example is like Vector, Map and its generic in nature, meaning, we can use them with any data types including our own. You must be looking for a developer who has expertise in all the mentioned technologies and also can write code with out bugs using G++ compiler of Linux. I have all of it and also experience of completing various projects successfully. If you hire me then I guarantee you that I will give you a work like GEM.