Ultratron had Steam trading card support added on August 6, 2013. There are 5 cards in the series, and you'll receive 3 cards at random for purchasing and playing the game.
Trading Cards
Foil Trading Cards
Badges
Level 1
Animus
Animus
Level 2
Reprisor
Reprisor
Level 3
Punisher
Punisher
Level 4
Retaliator
Retaliator
Level 5
Avenger
Avenger
Foil Badge
Vindicator
Vindicator
Booster Pack
Emoticons
:cherries:
(common)
(common)
:spider:
(common)
(common)
:strawberry:
(common)
(common)
:ultratron:
(uncommon)
(uncommon)
:rabbit:
(rare)
(rare)
Profile Backgrounds
Bellum
(common)
(common)
Ieunitas
(common)
(common)
Letum
(uncommon)
(uncommon)
Lues
(uncommon)
(uncommon)
Ultratron
(rare)
(rare)