GamesCom of course.
Source: http://www.vg247.com/2013/08/01/xcom-enemy-within-listings-appear-online/VG247 said:The heretofore unknown game was rated by the reliably spoilerific Korean ratings board for PC, PlayStation 3 and Xbox 360, and has also turned up on the more tenuous Steam Database.
The listings, which seem to have been first spotted by CVG, give no clue as to what the title may refer to.
A request for comment from 2K yielded the following statement:
Were looking forward to making an announcement on August 21. We dont have any further comment at this time.