My apologies to all that had to read through irrelevant messages.
Good, apology accepted. Now, let's start being constructive, shall we? There's work to be done in the area of the alien background. What I wrote up so far is that the aliens are a warlike species who like to conquer their neighbours, but maybe we should flesh that out a bit. Earlier, Level spoke about the alien language. I hadn't considered that yet. What if we do something with that? For example, what if it turns out a bit like this (excuse the pseudocode that I invented on the spot):
[event: after alien written language research]
The aliens turn out to use a written language that is uncannily similar to the old Egyptian hieroglyphs. Though most of the glyphs are radically different, some are almost verbatim. Phalanx scientists suggest a more detailed comparative study be undertaken at the old Egyptian buildings.
[mission: Giza]
In this scripted mission, Phalanx soldiers must secure the area near the Egyptian city of Giza. so scientists may study the pyramids in safety. Resistance is unexpectedly high, and as it turns out the aliens have built a military installation in the area.
[event: after research on giza]
Scientists have made a stunning discovery. Not only do the ancient Egypian hieroglyphs resemple the alien language, but with new insights in the working of the alien language, the old texts may be re-interpreted. It seems the aliens are actually mentioned on the walls of the pyramids, where they are referred to as gods. This would indicate the aliens have been to Earth before, thousands of years ago. How this is possible, our scientists can't say, but they think the aliens must already have been a space-faring race back then.
[event: some time after the previous event]
Our scientists have improved their understanding of the alien language, and have begun to understand some of the messages the aliens are sending each other. Though most of the messages are obscure and don't help us much, it is clear that the aliens do not talk about the current conflict in terms of warfare. It seems more like business, which is a puzzler to our scientists. To find out more, we must interrogate an alien who has more knowledge of the operation than regular foot soldiers. We recommend you capture a live ranking officer aboard a Warship-class or higher UFO, so we can question him.
[event: after research on live alien officer]
The picture is becoming clearer. The officer we interrogated was not very cooperative and refused to say much at first, but we found ways to change his mind. As far as we understand it, he said the alien fleet is here for what roughly describes as "annexation". Apparently, from the aliens' point of view, Earth is rightfully part of the Antarean Empire. It seems they don't consider the current conflict an invasion. They see it as finishing up business. Together with the revelation we found at Giza, this leads us to research the Egyptian connection more thoroughly.
[insert all sorts of requirements here, be creative, people]
[event: after research on "The Egyptian Connection"]
All the pieces have fallen into place. This conflict starts five thousand years ago, at the dawn of the Egyptian civilization. During this time, the Antareans first came to earth. They found a primitive world, rich in natural resources but devoid of any useful inhabitants who could manage the planet for them. The aliens singled out the humans as the most likely creatures to rise to dominance on the planet, and decided to set up a development project.
The aliens approached the humans and, after years of effort, managed to close a deal with them. The aliens would give the humans power, in the form of technology, to help the humans grow and gain mastery over planet Earth. In return, the humans swore allegiance to the Antareans. The aliens calculated that in five thousand years, the human race would have developed far enough to be ready to serve their Antarean masters.
For a few thousand years, all went according to plan. The Egyptians rose to power, and built a mighty empire. On hindsigth, many of their cultural traits make a lot of sense in the knowledge that the aliens seedes their civilization. Slavery, for example, is a typically Antarean trait. The godlike status of the pharaos might also be lead back onto alien technology, as may the famous curses of mummified pharaos.
But the plan went awry. Rather than grow into their role as vassals of the Antarean Empire, the humans degraded into superstition and decadence. The alien technology broke down, and today almost nothing of it remains. The Egyptian civilization was overtaken by the Roman Empire, which in turn collapsed under the weight of its own decadence.
Today, there is nothing left of the legacy of the first alien visit to Earth. Nothing remains that tells us of the pact the humans made five thousand years ago. But the aliens have not forgotten. They claim Earth as their own, and they are not about to haggle.
[after this, the fight continues, and research focuses on how to effectively defeat the alien annexation fleet. Basic ideas have been put forward, for now we're going with a large mothership.]
So, thoughts?
Note: though I didn't mention it explicitly, it is implied that old Egyptian gods like Ra, Bast, Osiris, Ptah, Indra, etc. are in fact names of aliens who came to Earth in 3000BC.