Here is the full list of all 31 Word Crack achievements.
Crack a 4 letter word
Crack a 5 letter word
Crack a 6 letter word
Crack a 4 letter word on the first guess
Crack a 5 letter word on the first guess
Crack a 6 letter word on the first guess
Submit a word that doesn't exist
Complete your first game
Get a score of 1000 or higher
Get a score of 2000 or higher
Get a score of 3000 or higher
Get a score of 4000 or higher
Get a score of 5000
Crack 10 four letter words
Crack 50 four letter words
Crack 100 four letter words
Crack 250 four letter words
Crack 500 four letter words
Crack 1000 four letter words
Crack 10 five letter words
Crack 50 five letter words
Crack 100 five letter words
Crack 250 five letter words
Crack 500 five letter words
Crack 1000 five letter words
Crack 5 six letter words
Crack 10 six letter words
Crack 50 six letter words
Crack 100 six letter words
Crack 250 six letter words
Crack 500 six letter words