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.
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.
Completed Episode 2: "A House Divided"
Settled things with a new friend.
Made it to the ski lodge.
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.
Reached the museum.
Survived the attack.
Got back on the road.
Completed Episode 4: "Amid the Ruins"
Made it out alive.
Took a breather.
Stopped for the night.
Reached the other side.
Made it through to morning.
Reached the terminus.
Found your way through.
Completed Episode 5: "No Going Back"