Letter Quest: Grimm's Journey Remastered

NOTE: The 2500 words can be in either story mode OR endless mode. Keep in mind that there's an achievement for spelling 750 words in ONLY endless mode too, so don't grind this out after you finish story mode before doing endless mode.

This will likely be one of the last achievements to unlock in the game and may require some grinding. After completing story mode and endless mode (including spelling 750 words in endless mode only) there's a very good chance you'll unlock this or be very close, which is highly dependent on how much you use the word solver (which assumes you're constantly using long words instead of many short words). The best way to grind out words is naturally to make a ton of three-letter words instead of longer words.

Once you've unlocked all of the other achievements and are ready to grind this out, go to stage 7 where you'll fight a giant bunny that takes no damage from 3-letter words. Equip books to improve your healing and defense, and then just spam him with 3-letter words, healing with potions as needed to stay alive. Eventually he will kill you, but by that time you'll have used a ton of 3-letter words and shouldn't have to repeat this for very long to reach 2500 words.