I actually met BinaryCounter there! I talked to him about an idea for Co-op multiplayer for Backpack Hero. He’s probably going to tell you about our meeting :)
The idea is basically a shared backpack, where each player has one half and can support the other player with their own items. Example: One player has a bow, the other has arrows. So they put their items up to the border so that one can give arrows to the others.
If BinaryCounter tells you that a kid at gamescom told him this, then it‘s me!