Full map EE Guide:

1a) turn off reactor (near laboratory teleporters)
1b) destroy 8 cameras (4 up, 4 down)
- up: cafe, offices/toilets, 2 outside (elevator building back side, bedrooms building by rocket launch button)
- down: drill tunnel, tester, reactor, Pistons
2) go to lab, click blue computer to unlock satellites
3) go to headcrab office (near tester) click blue lighted tape computer machine
SIDE EE: go to bedroom of dude, get white key, you can now get special moon buggy access
4) go to drill room, press button. Drill opens up secret room with steps
5) press button in secret room to spawn orange keys
6) find 8 orange keys (press e to collect), 12 possible spawn locations
- up: freezer, playground, rocks, toilets, bedroom behind couch, garage on crate
- down: crate near drill, inside crate small warehouse, pistons, reactor, vent shaft, behind window of tester room
7) have at minimum 3 people press the buttons in the launch centre jump puzzle at the same time (1 on far asteroid, 2 on main asteroid with 3 buttons. This step is easier with 4 people)
8) Launch rocket; ends game

Feels like a CoD Zombies easter egg to me but thanks