here is a cool little Easter Egg to get a special achievement in the new Extinction Map called "Nightfall". The achievement will get you an Xbox Live Achievement, plus 10,000 XP in the new map for Extinction which is Nightfall. This will help you rank up very fast and get better guns, perks and equipment to help you survive the alien hordes.
The actual bulk of work to get this achievement is done in public multiplayer games on the various new maps which are "Fog", "Bayview", "Containment" and "Ignition". There are 4 alien eggs growing in these maps you have to find. All you need to do is shoot them in order to activate the "Egg Hunter" task, and each time you shoot one, on the left hand side of your screen, it will flash up that you have 1, 2, 3 or all 4 of the eggs collected.
When you have them all collected, all you need to do is go into the "Nightfall" extinction map, and destroy a hive. Once destroyed an achievement will flash up giving you gamer points and 10,000XP to spend and use in perks etc in the setup equipment part of extinction.
Check out the video w if you are unsure where on the new levels the Eggs are located and how to activate them. This reveals all locations and shows you the achievement being given live in game.
Thanks for reading guys, stay tuned to the blog for more secrets and info!