Use a text editor to edit the "DefaultInput.Ini" file in the game folder, which is probably in 
the "C:\Program Files\Steam\steamapps\common\Antichamber\UDKGame\Config\" directory. 
Locate the following section:

[Engine.Console]

ConsoleKey=Tilde
TypeKey=Tab

;—————————————————————————————–
; Uncomment these to disable the console access
;—————————————————————————————–

ConsoleKey=None
TypeKey=None

Notice there are two entries for the "ConsoleKey" command. Change the second instance (the one 
that was originally "ConsoleKey=None") to any desired key (for example, "ConsoleKey=F12"). Then
while playing the game, press that key to display the console window. Type one of the following
codes and press [Enter] to activate the corresponding cheat function:

Result                                Cheat Code 	
-----------------------------------------------------
God mode                            - god
Toggle invisibility                 - invisible [0 or 1]
No clipping mode                    - ghost
Flight mode                         - fly
Disable no clipping or flight modes - walk
Toggle third person view            - behindview [0 or 1]
Set game speed; "1.0" is default    - slomo [number]