Short answers, pulled from the story.
The Federal Association of Interactive Entertainment Software hosted the Games Convention in Leipzig from 2002 to 2008. This event briefly became the largest games trade show in the world before logistical challenges emerged.
Gamescom was first held in August 2009 and proved extremely successful while Games Convention Online was discontinued after 2010. The BIU and Koelnmesse announced a new event circuit in 2008 to be held in Cologne beginning in 2009.
The event was streamed on the 19th of August at 8:00pm CEST during its inaugural year. Geoff Keighley began hosting Opening Night Live from 2019 as a streamed event at the beginning of the show.
The peak occurred in 2018 with 370,000 visitors and 1,037 exhibitors from 56 countries attending. Attendance grew steadily over subsequent years reaching 275,000 people in both 2011 and 2012 before rising to 355,000 in 2017.
Nvidia announced the GeForce RTX 20 Series at the Palladium Cologne on the 20th of August 2018. This announcement took place alongside other major reveals such as the PlayStation 3 Slim and Fable III.