Void Invaders was released on Steam with trading card support on August 14, 2015. There are 5 cards in the series, and you'll receive 3 cards at random for purchasing and playing the game.
Trading Cards
First boss
Second boss
Third boss
Fourth boss (UFO)
Fourth boss (monster)
Foil Cards
First boss
Second boss
Third boss
Fourth boss (UFO)
Fourth boss (monster)
Badges
Booster Pack
Emoticons
Profile Backgrounds