Well, 3DGS is a good engine to start with, but I wouldn't recommend a big 3D commercial game, with 3DGS you might want to stick with casual games. Seeing as you are going through a c++ course I'd recommend getting TGEA rather than 3DGS, it uses cpp and is more capable of pulling off a good commercial product. But like I said, if you want to play casually, use 3DGS, it's perfect for it.