Here is the full list of all 29 Rocketbirds: Hardboiled Chicken achievements. It takes around 10-12 hours to unlock all of the achievements on Windows.
Overthrow Putzki and liberate Albatropolis
Kill 300 penguins or clones
Find 3 Signs
Kill 10 enemies, each with one gunshot
Juggle an enemy for 10 seconds
Kill a helicopter penguin with his own missile
Kill 100 penguins or clones
Launch the silo missile
Complete the Cooperative game mode
Find 20 Signs
Find all 45 Signs
Kill 6 helicopter penguins with their own missiles
Escape the large zeppelin with 40 seconds or more on the timer
Kill 30 Penguins as they step out of a door
Brainbug 30 enemies
Brainbug the penguin above the star in Chapter 6 (Single Player)
Kill 20 enemies while brainbugging
Brainbug at least one penguin from each of the 7 penguin ranks, including Putzki
Kill Brno with the knife
Kill 2 enemies with one grenade
Kill 3 enemies with one grenade
Kill 6 enemies with the bazooka
Carry the other cooperative player for 500 meters in the same chapter without dying
Punch or kick 100 times
Kill an enemy by knocking him into a laser door
Stack all 3 crates near the end of Chapter 11 (Single Player)
Kill all penguins stationed on the zeppelin in Chapter 3 (Single Player)
Kill all penguins stationed on the small zeppelin in Chapter 8 (Single Player)
Kill all penguins stationed on the big zeppelin in Chapter 8 (Single Player)