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 4: "Amid the Ruins"
Learned new survival skills.
Returned to the meeting place.
Reached the museum.
Found the Observation Deck.
Survived the attack.
Got back on the road.
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.
Talked to a stranger.
Left the cabin.
Completed Episode 1: "All That Remains"
Helped someone through a difficult time.
Got what you needed.
Took care of yourself.
Headed out with the group.
Arrived at the cabin.
Met new people.
Found a campsite.
Arrived at the shore.
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"