Here is the full list of all 50 Ori and the Blind Forest achievements worth 1,000 gamerscore.
Completed the game
Reunited with Naru
Restored the Element of Warmth
Entered Mt. Horu
Killed 100 enemies with Charge Flame
Found 50% of all secrets
Earned all Efficiency Skills in the Ability Tree
Killed 50 enemies with Stomp
Obtained the Sunstone
Saved at every Spirit Portal
Escaped Kuro
Restored the winds of Nibel
Cleared the Misty Woods
Tricked 5 enemies into killing another enemy
Killed 500 enemies with Spirit Flame
Collected 200 Energy Shards
Killed 25 enemies using Bash to reflect projectiles
Killed 3 enemies without touching the ground
Restored 50% of all Map Stones
Escaped the rising waters of the Ginso Tree
Restored the heart of the Ginso Tree
Created 50 Soul Links
Double Jumped 5 times consecutively without touching the ground
Entered the Ginso Tree
Rescued Gumo
Caused an enemy to destroy itself
Crushed a Ram with a Stomper
Discovered Gumo
Killed 4 enemies simultaneously using Charge Flame.
Opened 5 shortcuts using the Charge Flame
Met the Spirit Tree
Restored your first Map Stone
Used your first ability point
Found your first secret
Completed the Prologue
Kill 5 enemies with Charge Jump
Find all secrets
Restore all Map Stones
Find the lost corridor in the Misty Woods
Visit 100% of the map
Earn all Utility Skills in the Ability Tree
Earn all Combat Skills in the Ability Tree
Earn all skills in the Ability Tree
Collect all Energy Cells
Collect all Health Cells
Juggle a rock 5 times without it hitting the ground
Bash off enemies 10 times in a row without touching the ground
Finish the game in under 3 hours
Complete whole game without dying
Complete the whole game without using an Ability Point