Millennium 5 - The Battle of the Millennium had Steam trading card support added on November 7, 2014. There are 8 cards in the series, 4 of which you'll receive for purchasing and playing the game.
This game is the sequel to Millennium - A New Hope, Millennium 2 - Take Me Higher, Millennium 3 - Cry Wolf and Millennium 4 - Beyond Sunset, all of which also have Steam trading cards.
Trading Cards
Foil Cards
Badges
Booster Pack
Emoticons
Profile Backgrounds