Counter-Strike

Vibrating subtitles and menus:
Enter UNDONE!! as a case-sensitive profile name.

Alternate Prodigy terrorists:
Enter PlumRugOfDoom as a case-sensitive profile name. The terrorists at Prodigy will now have purple streaked hair.

Hint: Airstrip: Get on roof:
At the B bomb (Counter Terrorist spawn), there is a way to get on the roof. You will need two people to do this. When you start, turn around and go to the bombed out "house". Jump on the bit of the house where you can, then jump up to the next part. If you need a running jump, you should use it but it is not necessary. You can now jump onto the tank. Run to the end and jump onto the boxes. Get one person to crouch down on the boxes and jump on his head. You can then jump onto the roof. When the Terrorists arrive to plant the bomb, you can take them out. To benefit the Terrorists, you can stop the Counter Terrorists from defusing the bombs.
tony.

Hint: Miami: Movie billboard:
Across the street from the bank at a theater, there is a billboard that reads "Half Life: The Movie starts Friday at 11".

Hint: Miami: Jump on top of movie billboard:
Get three players on top of the S.W.A.T. truck. Go to the edge and pile up on top of each other. Then, have the top person try to jump onto the billboard. Note: This may require a fourth player.
SepticFuddy.

Hint: Miltia: Smoke screen:
At the Counter-Terrorist spawn point, take a right and go over to the fence. Throw a smoke grenade over the fence so that the people on the other side cannot see you. Run straight back to the wall so that the fence is a slightly away from you. You should be able to see through the smoke, and shoot.
TenClub.

Hint: Safe demolition:
Buy the riot shield. Play the match normally until the bomb is planted. Find the bomb, but before diffusing it, press B to go into riot mode. You will not take any damage while diffusing the bomb.
brian bertrand.

Hint: Using shields:
Enemies will not shoot if you have the shield active. Use this to your advantage. When you spot an enemy, activate the shields secondary and call for backup. Also, whatever side you shield is on, it will deflect bullets that are coming from that side.
brian bertrand.

Hint: Avoid falling damage:
When you are about to do a big fall, equip your shield's secondary function, look straight down, and jump. You will take no damage.
brian bertrand.

Glitch: Aztec: Get stuck in wall:
Choose the CT side. Once you spawn, go down the nearby steps and turn right. Face toward the steps again and go to the right-hand corner of that small area. Crouch and turn around. Your character will now be stuck in the wall and cannot get out until he has been killed or the match ends.
Gary Ricker.

Glitch: Aztec: No damage:
Jump in water and you will not take damage for either team.
RanGotCaught3.

Glitch: Dust:
Counter-terrorists can take a straight left then crouch on the ledge above those stairs. Have a friend jump on your head. You can then jump on top of the map and shoot people through the hole in the floor/ceiling. This is only useful if the terrorists plan to go to B.
Toxn.

To get on top of tents, have a player crouch under one tent. Then, jump on his head. If both of you jump at the same time, you will land on top of it. You can now pick unsuspecting people off. It can benefit either team.

Glitch: Dust2: Invisible bomb:
Play on Dust2 on the terrorist team. Go to Site A with the bomb (two people required). Have one person get on the box close enough to the bomb site then he must kneel down in the center of the box, but leaning on the wall. The person with the bomb must get on the head of the player that is kneeling down. When on his head, you must be kneeling down. After kneeling plant the bomb on his head, move off his head. Then have the person with the bomb on his head slowly move towards the edge of the box. The bomb will slowly fall off and go in the box. It will become invisible, except for perhaps the red light. However, the CTS can not defuse it.
Josh Shaw.

If you kill an enemy very close to the bomb site then crouch directly above the body and plant the bomb, it is now invisible except for the little blinking light. However, if you throw a smoke grenade you should be all right.
jim jewer.

Glitch: Dust 2: Flash everyone inside tunnels:
Start as Counter Terrorist. Buy a flash bang or two and go towards the B bomb site. Before you get to the double doors, look to the left. There will be two boxes, one big and one small. Throw the flash bang between the two boxes. This will flash everyone inside the tunnels.
Eric Young.

Glitch: Italy: Hidden location:
When you get to the alleyway with the tunnel on the right and the path to the wine cellar steps on the left, take the left path. A little nook is there. Have a player crouch there. You can jump on his head, then jump to another nook that no one looks for.
Toxn.

Glitch: Italy: Flying hostage:
When you start as a Counter Terrorist, you must to choose the left or right. Select the right. Notice the wall to your left, which splits up the directions to go. Notice that there is a small gray sidewalk that goes up hill. Follow this until you stop going uphill. You should now be where you need to put your hostage. Get a hostage. Tell the hostage to quit following you by going up to him and pressing X. Then, push him all the way up against the wall at the top of that hill. Make sure he stays on the sidewalk. Then, get behind him and start pushing him downhill. If he slowly starts to float, you are doing this correctly. Push him all the way down until you reach the edge of the building, then stop. He should be floating over your head. Then, push him up by jumping up from under him and he should start to slowly fly up to the top of the building. The only way to get them down is to shoot them.
TenClub.

Glitch: Miami: Enter invisible vent:
Play as either team. Go to the hallway in the bank near the terrorist spawn point. Go to the room with the desk and the two hostages inside (two people required). When inside, look near the hostages. You will see that part of the ceiling is falling. Go on the desk with the computer and the chair. Once there, have one of the players kneel down and line up with the ceiling peace that is falling. Then, have the other player jump up on the person that is kneeling. Jump on his head then kneel down on his head. Have the person on the bottom jump up and the other player jump at the same time and stay kneeling. If done correctly, you will end up in a hidden vent which you will be stuck in. You can shoot out of two places where the ceiling is falling and you can see a hostage's head. You can shoot out there and at the other side with the opening. You can shoot out there through the door. Note You cannot get out, but can shoot just enough to hit someone coming in.
Josh Shaw.

Glitch: Miltia:
Go on the roof, line up with the tree on left side, then run and jump and you will land in it. This benefits the terrorist team.
Toxn.

Go to the last sewer and jump on the rocks that surround it. Then, push towards it and you will go in the wall and become about 98% covered. This benefits the terrorist team.
Toxn.

Go to the counter-terrorist spawn point and climb up the rock on the left. From there, jump to the top of the right fence. Walk along it until you hit the wall, then look for the white flaw in the wallpaper of the map. Jump on that white line and follow it. From there you can jump onto the top of the sign and camp. This benefits either team, depending on the situation (camping counter-terrorists or terrorists trying to pick off counter-terrorists rescuing hostages.
Toxn.

Glitch: Militia: Super flash:
Start out on the Counter Terrorist side. There is is a fence next to the spawn point. Next to the fence is a rock. To the right of the rock there is a rock wall. At the bottom of this wall is a mini crack that runs next to the ground. Throw a flash grenade under there. It should flash all the people in range near the second manhole by the hostage building. This is an annoying skill.
Spartan7593.

Glitch: Piranesi: Swimming:
Note: You must have a Defender and have friendly fire on. At the terrorist spawn point, go to the top of the ramp. Then, go left and jump onto railing or ledge against the wall. Crouch down and have a teammate get on top of you. Then, have him jump towards the left of the wall. When he is as high as he can go, shoot him using burst fire. He will end up swimming in the water
Elite Forces.

Glitch: Piranesi: Leave level boundary:
Get three teammates and go to Counter-Terrorist spawn point. Get on top of the car (not the tank) and at the end, then boost two of the players onto the ledge. Next have one player crouch down and boost the other over the fence.
Elite Forces.

Glitch: Piranesi: Get into tree:
Use the "No falling damage" glitch after going to the roof. Aim for the tree. This is difficult and may require a few attempts. Note: This provides great cover for Terrorists.
Elite Forces.

Glitch: Prodigy: Go above level:
To go above the level, start as a counter-terrorist with a friend. Have both players go up the stairs towards the open area with the room with the window. That room has a ladder on the back of it. Have both players climb the ladder and go to the top right corner of the room. Jump towards the wall and you will land on an almost invisible ledge. Scale the ledge around the corner. Then, have your friend jump on your head, then to the top of the level. You can follow that wall quite a while until you are lined up with a very nice place to kill terrorists as they run out of the tunnel.
Toxn.

Glitch: Stadium: Get on top of light fixture:
Go to bombsite A. Get on top of the table at the bottom right (when coming from the Terrorist spawn point). Crouch, then boost a teammate onto the light fixture.
Elite Forces.

Glitch: Stadium: Get on top of a tree:
Proceed from the Terrorist spawn point to bombsite B. On your way, there is a tree in the middle of the passage. Get a teammate to boost you up onto it. You can then throw a smoke bomb from there to provide extra cover.
Elite Forces.

Glitch: Truth: Reach top of level:
From the Counter-Terrorist spawn point, go right, then left, then right. Get on top of the smallest box. Have a teammate get on top of you, then boost him onto the top of the level. Note: This may take some time.
Elite Forces.

Glitch: Retrieving hostages:
Counter-terrorists can retrieve hostages by jumping and pressing X on the floor below the hostages instead of having to walk upstairs, where terrorists like to camp.
Toxn.

Glitch: Wrong weapon sounds:
Have a primary and secondary gun. At any time, press Fire and Switch Weapon at the same time. If done correctly, if you had a primary weapon it will switch to secondary and will look and sound as if you shot the primary gun and vice versa. Also, and no ammunition will be used.
mouse17525.

Glitch: Popcorn grenade:
The best map to use this trick on is Militia. Join a Militia map and play as a Counter-Terrorist. This will give you a closer position to the glitch. When you start, buy a Smoke Grenade. Then, go through the tunnel to the left which leads to the fence and the rocks that make a ladder over the fence. Jump the fence and turn to the left. You will see a rock hill. Go up the hill, but do not jump off. You will see a crack between the rock and the wall. Take out the Smoke Grenade, point straight down in the crack, and throw it. You will hear a crackling, like popcorn.
LONNIE.

In the terrorist spawn point on Miltia, there is a bed. Take a smoke grenade and get on the bed. Look down in the corner of the foot board. Throw the smoke grenade in that crack.
TenClub.

As a Counter-Terrorist, at the Dust 2 spawn point turn to the right and go to Bombsite B. Before entering the double doors toward the bombsite, there is a wooden box and stone crate to the left. Between the box and crate is a crooked space. Use your smoke bomb and throw it down. The Terrorist team can also do this trick.
Ka Pinoy.

Glitch: No falling damage:
Use the shield and have a teammate shoot it two times. If you now fall off a bridge, you may not take falling damage. This works about 70% of the time.
Zach McCarthy.

Glitch: Super jump:
On any level turn, on "Friendly Fire". Have one player kneel down, then jump on top of their head. Next, have them aim at you with their gun. Make sure you have full armor. Begin jumping on their head. When you are at the highest point of you jump, have the other player shoot you. This is useful in Miami in the lobby, where you can use it to shoot people up in the hole in the ceiling.
TenClub.