So much that they would go to the trouble to conquer the planet? The biological diversity to incorporate into their Combine, granted. But what in the way of resources? If all the Combine wanted was the biological bits and peices that they can pick off of Earth, they would have abducted (hehehe), the various samples that they wanted and left. Why would they want to go to the trouble of completely conquering Earth? Something has to be keeping them here that they want. Water? They seem to be draining Earth of its water supply, and water has characteristics that nothing else currently in existence does. Also, in all the Combine technology seen thus far, water has not been extremely taken advantage of. I admit that it is not very likely. Then again, we do not know the biological processes of the original combine. Maybe they do not need water, or it did not exist in the universe from whence they came. I am just confused as to why they are draining the water. Why? Also, why are they still here? What do they want?