Here is the full list of all 40 The Walking Dead: Season 2 achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Completed Episode 5: "No Going Back"
Found your way through.
Reached the terminus.
Made it through to morning.
Reached the other side.
Stopped for the night.
Took a breather.
Made it out alive.
Completed Episode 4: "Amid the Ruins"
Got back on the road.
Survived the attack.
Reached the museum.
Found the Observation Deck.
Returned to the meeting place.
Learned new survival skills.
Got separated from the group.
Completed Episode 3: "In Harm's Way"
Gave what you got.
Invited some friends into the compound.
Got beaten down.
Committed larceny.
Made it through your first day.
Witnessed a murder.
Arrived at your new home.
Met someone on a bridge.
Found a way across the water.
Left the cabin.
Talked to a stranger.
Helped someone through a difficult time.
Completed Episode 1: "All That Remains"
Headed out with the group.
Took care of yourself.
Got what you needed.
Arrived at the cabin.
Met new people.
Found a campsite.
Arrived at the shore.
Made it to the ski lodge.
Settled things with a new friend.
Completed Episode 2: "A House Divided"