1_eye
aperture_logo
artificial_intelligence
blue_eyes
blurred_background
device
duo
g-man
glados
gravity_gun
half-life
hi_res
holding_object
human
looking_at_device
machine
male
mammal
nitro-killer
not_furry
out_of_focus
portal_(series)
portal_gun
robot
unforeseen_consequences
valve
valve_corporation
