Deponia: The Complete Journey had Steam trading card support added on 9 July 2014. There are 8 cards in the series, and you'll receive 4 cards at random for purchasing and playing the game.
The other installments in the game series, Deponia, Chaos on Deponia and Goodbye Deponia, also have trading card support. However, Deponia: The Complete Journey is a modified version of all three games that has its own card set, not the cards from the separate Deponia games.