A King has his reign. Then he dies.

I posted the following as a response earlier and I meant to post it as a "Start a Discussion". Don't read any further if you don't like possible spoilers: Here goes: Invitations to a graduation party have been left behind on many habitable planets by the Engineers who have seeded these planets thousands of years in the past. The only requirement is that the species being invited need to be aware that they have been invited and have the means to get to the party. Humans find the invitation and head off to the party following the directions left behind. Unbeknownst to the humans, another species arrives first but have other plans. They want to be the new "Kings" on the block. What do new "Kings" do? On earth, some Kings kill off all of the old Kings children so there will be no retributions or acts of vengeance at a later date. But there is only one problem. The new "Kings" don't know where all the children live (earth) or where the earth is. Or for that matter where all the other seeded "earths" are. Invitations were left behind on several planets represented by the pyramids visisble as Prometheus comes in for a landing. Each pyramid represents a different planet seeded by the Elders (Engineers). Each pyramid contains artificats that will be vaguely familiar to each species when they get around to exploring their particular pyramid. Our pyramid has the big head with the ampules containing the either the bioformer used to seed our particular planet or the roach bait to wipe out whoever comes by. The Blue Meanies are the species that beat us to the party. They are the equivalent of child molesters 3rd class. They have laid a trap for all the other species invited. As the new species arrive for their diploma, the Blue Meanies annihilate them (after getting the directions back to their home planet, of course). They then follow the directions to that home planet and kill all the children with the Bio-Weapons they have on board their space vehicle. They use the space cannon/wormhole creator thingy to eradicate the "children". When they are thru killing the "children", they have a turn-key planet to propagate their species. They then return to the Engineers planet and set the trap for the next species. Eventually, they will get directions to all of the habitable planets that the Engineers seeded. Not only are they bad, they are lazy too! But something goes wrong with the Blue Meanies plan. The humans figure out that its a trap and open up a can of "whup-ass" on the Blue Meanies. We may be smaller than them, but we are pure of heart and we manage to bring down their space vehicle. However, we now have no way to get home. I don't think we have seen the Engineers yet in any of the trailers. I think they are a dying, benevolant race that meant well but some of their "children" turned out bad, really bad. Anyway, that's my theory. You are free to blow holes in it. Criticism is appreciated.