How to play: Stack words to build a tower all the way to the top of the screen. Each round gives you a set of blank tiles to fill, with one catch: There's a "locked letter" in every line. It's the same letter for the whole game. You fill the blank tiles around it to spell a valid word.

Those are the basics, but here are some "good to know"s:

– You can only use the same word once in a game

– Including rarer letters will increase your score

– There are three levels, where the locked letter changes (and the difficulty ramps up!)

– There's no timer, so feel free to ponder fun and/or rare words