Jump down the building. Place the corner of the building in front of you. Go to the right side, and all the way in the left corner. There is a teddy bear on one of the columns of a planter.
Play the first chapter. You will have a chance to flank some CELL soldiers by entering a small sewer after the subway. Notice the electrical wires hanging above that are marked "Caution 1.21 Gigawatts".Actual Easter Eggs
Look for a news stand while exploring the city. A picture of Crytek's CEO will appear on a magazine cover.
After five consecutive deaths the "Deflection" message will appear. It will disappear after you get a kill.
Play the second chapter. Get to the point where you are on the roof with the donut to your left. Wait until the people near the pit of burning dead bodies break up. One of the Cell Soldiers will eventually walk under the donut. Knock it off with a melee attack to earn the achievement or trophy.
During the "Dark Heart" chapter in Campaign mode. You will be asked to do a Tactical Assessment. One of them will be "Avoid" because of a deep sink hole. Throw a Ceph into the hole to earn the achievement or trophy.