C++ is among the top of the widely used languages for games. It retains the quick execution speed of C, and brings in much needed and required things such as objects and class inheritance (OOP). Naturally, you'd be using graphics libraries with this, such as OpenGL or DirectX. Possibly even also pre-made engines (Unreal, Crytek, etc.) if you have the hundreds to thousands of dollars.
Programming language aside, you'll also need a very strong understanding of advanced mathematics, for 3D math.