That's a good question, I guess I didn't make that too clear.  I guess I really didn't want the gems' invasion to be much further along than it ever got in the actual show, as they apparently managed to establish what basically amounts to a spawning point on Earth.  The biggest thing I intended to be different is that the gems have already successfully put down an organized resistance on Calyx, while in the show it's very ambiguous whether or not humans as a whole were ever aware of the gems.