Complete the following tasks to unlock the corresponding achievement. To view your achievements and stats in Steam, select "Community", then "My profile", then "View all my games", then the game and view stats.

Down to the Green: Win consecutive all-ins.
Flush: Win a hand with a Flush.
Four of a Kind: Win a hand with Four of a Kind.
Full House: Win a hand with a Full House.
Kicker Trouble: Win a showdown where you and the opponent have same hand (pair or better) and you have a better kicker.
Rags to Riches: Win a showdown with just a high card.
Rushing: Win three straight pots.
Slow Play: Check a pat hand.
Special Item: Max: Knock out Max after he's bought in with his special item.
Special Item: Strong Bad: Knock out Strong Bad after he's bought in with his special item.
Special Item: The Heavy: Knock out The Heavy after he's bought in with his special item.
Special Item: Tycho: Knock out Tycho after he's bought in with his special item.
Straight: Win a hand with a Straight.
Straight Flush: Win a hand with a Straight Flush.
Triple Through: Win a pot with two or more opponents when you are all in.
Win A Game: Win a full game.
Win A Game, Hard: Win a game on hard.