Here is the full list of all 17 Giana Sisters: Twisted Dreams - there are Director's Cut achievements worth 1,000 gamerscore.
Unlock Über Hardcore Mode
Obtain a trophy in all Score Attack levels
Obtain a trophy in all Time Attack levels
Obtain five stars in all levels in hard mode (except Extra levels)
Collect all gems in the game (except Extra levels)
Defeat the Owlverlord in on normal difficulty or higher
Defeat Gurglewocky
Defeat Octor Freud
Use a spiky box like a trampoline
Unlock Hardcore Mode
Defeat Hansel + Gretel
Land on an owl while twirling
Bounce off a falling turtle
Jump or dash onto three owls without touching the ground
Collect a yellow gem while dashing
Collect a red gem while twirling
Unlock the power to warp your dreams.