Strike Suit Zero: Director's Cut had Steam trading card support added on April 8, 2014. There are 5 cards in the series, and you'll receive 3 cards at random for purchasing and playing the game.
This is an enhanced version of the game Strike Suit Zero, which also has trading cards, but a different set. You won't receive cards from the regular set by purchasing the Director's Cut version of the game, or vice versa. Strike Suit Infinity also has trading card support.