Ok, I gonna tell you some cool easter eggs but not all just 5 or 4
So.. If you on anticitiezen one Than theres a easter egg Some where in a house I dont know how it called i was in it i saw a tv that wasnt plugged-in and i saw gman and dr.kleiner on the tv and it plays the gman song that song is pretty scary ok heres the list of all Point Insertion
* Sighting 1 - (map: d1_trainstation_01) You first see the G-Man in a hallucination on the train introducing you to the game.
"A Red Letter Day"
* Sighting 2 - (map: d1_trainstation_05): If Gordon flips through the main monitor in Kleiner's Lab a few times, eventually it will come across the G-Man staring at the other side of a fence. G-Man walks away shortly thereafter.
Route Kanal
* Sighting 3 - (map: d1_canals_01): In a resistance member's boxcar, a TV temporarily shows the G-Man, with a Vortigaunt watching and supplying television power. The G-Man appears to be in the same "studio" where Dr. Breen delivers his televised messages to City 17, complete with the Combine's logo.
Water Hazard
* Sighting 4 - (map: d1_canals_06): He is seen standing on a pier in front of the headcrab infested Station 7. As Gordon approaches, he disappears inside.
* Sighting 5 - (map: d1_canals_06): Vaguely seen in a large rectangular monitor that flickers his image along with other broadcasts.
* Sighting 6 - (map: d1_canals_12): After Gordon spots a Carrier Synth, the G-Man can be seen overlooking a ledge as Gordon's airboat passes under.
* Sighting 7 - (map: d1_canals_13): Before Black Mesa East, the G-Man can be spotted on a concrete ledge near the gate controls. However, once Gordon turns a wheel to raise a gate blocking his progress, the G-Man is no where to be found. Coincendently, there is a sign pointing to where G-Man stood which states "Observation".
"We Don't Go To Ravenholm"
* Sighting 8 - (map: d1_town_05): After leaving Ravenholm, he can barely be seen walking off into a tunnel behind a few train cars.
Highway 17
* Sighting 9 - (map: d2_coast_03): Looking through the Combine binoculars at the second house the player comes to on Highway 17, Gordon can spot the G-Man conversing with Colonel Odessa Cubbage at New Little Odessa.
Nova Prospekt
* Sighting 10 - (map: d2_prison_02): Seen peering through a door window while nodding as Gordon flips through the monitors near the beginning of the prison.
Anticitizen One
* Sighting 11 - (map: d3_c17_02): In a ruined tenement building in City 17, an image of the G-Man standing in a wooden boat with a crow on his shoulder is seen briefly on a television along with some very discordant music. Strangely, the TV is unplugged, and if the player approaches the TV it will explode.
* Sighting 12 - (map: d3_c17_03): Similar to the giant rectangular monitor seen in the canals, the G-Man's image flickers on and off with Doctor Breen's, before the monitor is toppled by resistance members.
Dark Energy
* Sighting 13 - (map: d3_citadel_05): After you stop Dr. Breen from going though the portal, the G-Man appears at the very end of the game.