Here is the full list of all 51 Trine 2: The Complete Story achievements worth 1,000 gamerscore.
Earn all Achievements in Trine 2
Collect all experience in The Story Begins
Collect all experience in Forlorn Wilderness
Collect all experience in Mudwater Dale
Collect all experience in Mosslight Marsh
Collect all experience in Petrified Tree
Collect all experience in Shadowed Halls
Collect all experience in Hushing Grove
Collect all experience in Mushroom Caves
Collect all experience in Mushroom Murk
Collect all experience in Searock Castle
Collect all experience in Eldritch Passages
Collect all experience in Icewarden Keep
Collect all experience in The Final Chapter
Collect all experience in The Heroes Return
Collect all experience in Deadly Dustland
Collect all experience in Belly of the Beast
Collect all experience in Brackenridge Rise
Collect all experience in Cloudy Isles
Collect all experience in Goblin Machinations
Glide for five seconds with Kitesail Shield while having an object or character on top of the shield
Make goblins die of three different environmental hazards in a single level
Feed carnivorous plants with three or more different kinds of treats
Kill an enemy with a thrown hammer bouncing at least once before kill
Using grapple, swing around an object and reattach grapple again without touching any surface
Get at least 10 enemies killed by other enemies' actions in a single level
Make a bubble sink for three seconds
Stand on a plank floating on a single airflow for four seconds
Stand on a conjured box bouncing on any bouncy surface for 10 seconds
Shoot three arrows in the air and catch them all with the Knight's shield
Kill a grenadier goblin with its own cannonball
Construct a tower made of eight objects and stand on top of it
Capture three different types of enemies inside boxes and stack them on top of another
Build a 3-piece/character tower where lowest part is Pontius and his shield. Stand at least 5 sec.
Make a sandworm kill another sandworm
Capture a goblin in a Monster Prison and then launch it with a catapult
Throw a box with Pontius' magnetic shield and catch it or have another player catch it
Kill an enemy with an airborne object tossed with the Knight's charge
Shatter three frozen enemies within one second
Freeze two enemies and stack them on top of each other
Kick 5 enemies of the same kind into a bottomless pit with the grappling hook or the Shield glide
Create a makeshift raft of three separate parts and have a goblin sail it for five seconds
Launch an object with Knight's magnetic shield and break it with hammer before it touches the ground
Complete a level with only Amadeus
Complete a level with only Zoya
Complete a level with only Pontius
Complete the game
Finish a level without taking any damage (except in the Story Begins)
Find all chests in the game
Collect all experience pickups in the game
Complete the game on hard using hardcore mode