Duke Nukem 3D: Megaton Edition was a supported title that has since been removed from the Steam Store.
Duke Nukem 3D: Megaton Edition had Steam trading card support added on 30 August 2013. There are 6 cards in the series, and you'll receive 3 cards at random for purchasing and playing the game.
As of 15 February 2016 [1], the game has been removed from the Steam Store. However, its trading cards and crafting rewards are still available for selling and purchasing on the community market in addition to the ability to trade them.
Trading Cards
Foil Cards
Badges
Booster Pack
Emoticons
Profile Backgrounds