Here is the full list of all 10 Alphabear: Hardcover Edition achievements.
Make a 10 letter word
Score at least 4,000 points in a timed game
Make a single bear that fills the entire board
Make an 8 letter word
Make a wide 1(h) x 7(1) bear
Make a tall 7(h) x 1(w) bear
Score at least 2,000 points in a timed game
Make a square 5(h) x 5(w) bear
Score at least 10,000 points in a timed game
Add a legendary bear to your collection