Sleeping Dogs was a supported title that has since been removed from the Steam Store.
Sleeping Dogs had Steam trading card support added on 12 July 2013. There are 8 cards in the series, and you'll receive 4 cards at random for purchasing and playing the game.
The game has since been delisted from the Steam store (with the exception of the DLCs), due to the release of an updated version named Sleeping Dogs: Definitive Edition. However, its trading cards and crafting rewards remains available for selling and purchasing on the community market in addition to the ability to trade for them.
Trading Cards
Foil Cards
Badges
Booster Pack
Emoticons
Profile Backgrounds