Find an object then enable the bind "npc_create npc_antlion" code. Repeatedly press the bound key to spawn antlions.
Just inside the room where you watch the video from Judith, look next to the door to see a caged area with boxes. Destroy or remove the boxes in order to find a cover for a HEV charging station, just like in the original Half-Life.
Set the system date to October 31. After you are ambushed by Hunters and Combine at a big house, drive along the road. Near where the supply cache is found you will see an old truck. Go up to it. There will be lots of pumpkins lying on the ground.
Created by jer9carver.
When you enter the White Forest base, you meet a Vortigaunt in a lab coat named Uriah. When you first enter the room where you meet Uriah, there is a gas tank against the back wall. Behind that tank is a small room with a computer that has a sequence of numbers on it. This is a reference to the show Lost that Gabe Newell added due to the fact that he and the creator of Lost were close friends.
G-man can be seen in the "Under The Radar" episode, entering the White Forest Inn immediately after the cache in the small cave. Once you get the cache, get in your car and drive into the two dead trees past the guard rail. Use the turbo just when you are between them, then follow the road. You will see him enter the inn and, if your timing is good enough and you do not crash into anything, disappear. This may require several attempts.