Letter Quest: Grimm's Journey Remastered

Treasure chests appear in some levels between enemies, and you open them by successfully finishing a Hangman-style minigame. You'll be given the full alphabet and have a set number of guesses to figure out the word.

This will likely come naturally, since you'll be playing each stage a minimum of 4 times to get all the stars in it, and there are more than 3 stages with treasure chests.

I only ever failed at unlocking one treasure chest (aside from the ones I did on purpose) by using the following strategy: first, guess E, R, and T. If there are still large gaps of letters where vowels clearly need to be, guess A. If there are still gaps, guess O, I, and U, stopping whenever it looks like you've probably gotten all the vowels. Then move on to S, N, and L. Nine times out of ten this should give you enough letters to figure out the word. If not, you can use a Hangman solver to help out.