Here is the full list of all 24 Owlboy achievements worth 1,000 gamerscore. It takes around 10-12 hours to unlock all of the achievements on Xbox One.
Master trinket collection at Buccanary's!
Unlock every trinket from Buccanary's shop
Collect all Buccanary coins
Collect every Buccanary coin from all zones
Clear the Boguin's Cannon Challenge
Collect the Golden disks
Listen to the shell near the old ruins
Beat Geddy 1000 times
Played Otus's song on Bomboman's drums
Learn how to cope with the heat in Toby's hot spring
Try to report to Asio at the first sign of trouble
Throw Geddy into the clouds! How rude!
Geddy joins your team!
Obtain the Strange Device
Alphonse joins your team!
Escaped the Frog Guardian
Survived the Destruction of Advent
Defeat the Security System
Defeated the Molten Guardian
Twig joins your team!
What are you doing, Owlboy?!
Beat the game
Enjoy your explosive surprise after rescuing the Boguin Brothers
Master Owlboy in all possible ways