Half-Life 2

When you enter Dr. Kliener's lab, there is a largeamount of items that you can just pick up and toss around: books,boxes, computer monitors, a mini cactus, and Dr. Kliener's clipboard with the information for your Hazard Suit on it. If youtoss things around the lab for long enough, Dr. Kliener, Barneyor Alyx will say something to you:

Dr. Kliener: "Oh, do be careful."; "Careful."; and "Oh dear."

Barney: "Whoa, careful." and "You're pushing it, Gordon."

Alyx: "Careful." and "Take it easy, Gordon. "

Note: It will take a lot of attempts to make Alyx, Barney or Dr.Kliener say something -- be patient.

• After the credits, wait to see the headcrab, Lamar, being pursued by the scientist. Then, watch him pounce on your head.
  

• After you complete the game, watch the credits. Note: They cannot be skipped. When you reach the end of the credits, you will see Lamar jump onscreen. You will then hear Dr. Kliener say, "Lamar? Blast that little… Where did she get to?" This is the same thing that he says when you first see him looking for her. Lamar will then lash out at you and supposedly "couple with your head".
  

To kill the Barnicals, let them pull you up, than hitthem with a crowbar from a short distance.

If you find it difficult to hit the Striders (or anyother enemy) with the RPG from far away, fire a rocket and immediatelypress [Zoom]. You will automaticallyzoom in like normal, but will still have control of the rocket.This helps in the later levels when you do not want to get tooclose to the Striders, or other enemies like the Combines.

Take something like a barrel, chair, or another objectwith the Zero-Point Energy gun. Enemies cannot hurt you when theyare shooting you. For better results, crouch when you are defendingyourself.

Barnacles are the enemies that are glued to the ceiling, with a long tongue that grab anyone passing underneath. In the "Route Kanal" chapter you will arrive in an area full of barnacles. Roll the explosive barrel nearby then shoot it when the barnacles grab it. The explosion should kill at least five barnacles.

Defeat the Antlion Guardian in Sandtraps. A Vort will offer you some balls called Pheropod that can attract Antlions. You can use them on enemies in the rest of the level and in Nova Prospekt. Note: Antlions will not attack you anymore.

In Chapter 11, "Follow Freeman", there will be a sniper shooting at you from the far end of the street. Move from cover to cover until you get close enough to toss a grenade or shoot an RPG into his window. Perpendicular to that street is another street also with a sniper at the far end. Reach the rubble that is blocking the end of that street. Hide behind the rubble so the sniper does not shoot at you, but you can still see the window. Save the game. Aim your grenade higher than the window to have it reach inside. If you run out of grenades, reload the saved game. Later in the level you have to climb onto a roofless building in order to save Barney. During this time, a sniper will shoot zombies in front of you. Wait for him to complete the job, then throw a grenade at him. Note: If you are low on grenades, there is a cache in the middle of the floor. After reaching Barney on the top floor, you will encounter two more snipers; one to the left and another in front. Return to the previous cache if needed to get more grenades.

Go to "Nova Prospekt" and find the toilet in one of the cells. Take it with the Gravity Gun, climb down the stairs, and look in one of the cells to find a hole with a headcrab inside. Throw the toilet on it to kill it.

This is possible after reaching the "Nova Prospekt" chapter or later. When Manhacks attacks, catch them using the Gravity Gun and throw it at your enemies.