Here is a collection of announcement and gameplay trailers for games at Gamescom 2019...

Humankind

Official Announcement Trailer

Ghostrunner

Official Reveal Trailer 2019

Little Nightmares II

Announce Trailer

Destiny 2: Shadowkeep

Gamescom Trailer

Watch Dogs: Legion

Gamescom 2019 - Play as Anyone Explained

Death Stranding

Gameplay Demo Gamescom 2019

Marvel's Avengers

A-Day Prologue Gameplay Footage

Need for Speed: Heat

Official Gameplay Trailer