Added a lot of new areas
Changed some stuff to look more like the PS2 version of Half-Life
Probably more stuff that I can't remember

Added the airlock
Added "soundscapes" (it's really just a looping sound that you can barely hear though)
Made it so you can open the doors with the use key
Added a door frame to the elevator doors
Added alarms
Changed floor textures in the eating area
Changed the size of some rooms to make my ocd happy (it breaks AI nodes in one place though)

Added locker room (and a bathroom with a working mirror)
Added an eating area
Added directional lines on the walls
Added more of Sector C
Changed the curved walls to be more like HL1
Fixed the computer monitor gibs being missing textures

Added another office
Added cubemaps
Added HDR support
Made a doorway bigger

Initial addon creation.