My first game done in OpenGL/C++ was the classic Tetris. I was quite proud of the hardcoded introductory animation.
So I started to play around car physics, collision detection, terrain based friction and so on. Although this little OpenGL/C++ prototype wasn't finished it was quite fun to develop and to play with.
In the game you're the last human on an earth full of robots and other creatures. Your mission is to decypher the human's genome and to find out how to generate new humans.
Eguin was a adventure game based on the popular Myst. As in that game the 3D scenes were pre-rendered.