Arch is correct, though without going off topic, the issue with skyboxes is that the camera in Glest almost never rotates to see the sky. As well, take a closer look at having the camera sidewise, and you'll see how the fog of war doesn't really work well with the concept of a skybox, as well as how graphically intensive rendering so many trees is at such a camera angle. Since Glest changes from day to night as well, a basic skybox would look rediculous, and an animated skybox would be a lot of work. The only true advantage would be the water reflectivity, though our shaders have a long way to go before we even have realistic water, much less reflecting a sky.