Half-Life: Opposing Force Cheats

Lockers
Just like in Half Life where the names of some of the people who made it were put around the lockers in the locker room, the names of some of the people who made Opposing Force are also in certain places e.g. at the start of the boot camp level look at the names on the boxes beside the beds.

Trash Compactor
The 'trash compactor' in the "Pit Worm's nest" level is right out of starwars (look at the doors and the pattern of lights above the doors).

DMM
Start the "boot camp" and type /noclip in the console to walk through walls. Go straight through the floor then and you reach a room with the hidden message "DMM 1999". DMM 1999 refers to David Michael Mertz 1999, the creator of the bootcamp.

Man in the Suit
If you're really curious about the man in the suit, you can use the "noclip" cheat code to walk throughs walls and doors to follow him. You will see him adjusting warheads and you even can take a look inside his briefcase.

Take a good look at Freeman
It's possible to take a good look at Freeman (I'm not talking about the various pictures on the wall). At the beginning of Level 5 'We are not alone, listen carefully, you'll hear a scientist encouraging "Freeman" to hurry. That's Gordon Freeman, the character players portrayed in the original Half-Life! Try leaping into the orb to follow him to Xen. Unfortunately, you don't land over a platform like he did. For more fun, switch to noclip mode and warp inside. You can get a good look at Freeman then.

Kids
This easter egg gives some problems, becaue I don't recall in which level I found it. Anyway, somewhere, there's a filing cabinet/desk lying on the floor next to a picture of Gordon Freeman. If you crouch and look at the desk, there's a picture of two kids. I assume they're the kids of one of the programmers.

Ultrasound
In the first level after the crash, a zombie throws a scientist through a window. If you run around the zombie into the lab, you'll see a computer with an ultrasound image. That ultrasound is of Randall Steward Pitchford III, the son of Randy Pitchford (the leader of Gearbox Software who developed Opposing Force). He was born on January 8, after the game shipped!

MS Windows
There's a computer in the room where you meet Otis for the first time that looks like it's running MS Windows. If you use the keyboard five times, the computer will crash with the "blue screen of death."

The Boss
When you are versing the boss of Half-Life: Opposing Force, stay still and he wont notice you, if you fire or move he willattack you.