Here is the full list of all 30 Squish and the Corrupted Crystal achievements worth 1,000 gamerscore.
Die at least 100 times.
Complete the first level.
Complete any level with gold time.
Complete a level in 12 seconds or less.
Collect all the crystals in any level.
Find the first alternate exit in Grasslands.
Find the second alternate exit in Grasslands.
Find the first alternate exit in Woodlands.
Find the second alternate exit in Woodlands.
Find the third alternate exit in Woodlands.
Find the alternate exit in Canyon.
Find the first alternate exit in Cloud Sea.
Find the second alternate exit in Cloud Sea.
Find the alternate exit in Crystal Cavern.
Collect a token.
Free Maji from the corruption.
Free Mwiba from the corruption.
Free Upepo from the corruption.
Free Ulizini from the corruption.
Complete Grasslands
Complete Woodlands.
Complete Canyon.
Complete Cloud Sea.
Complete Crystal Core.
Earn gold time in every level.
Collect every crystal in any level.
Collect all tokens.
Earn 100% completion.
Ascended to the top of the tree trunk in Diacris.
Find all hidden exits.