You find words in a grid, Boggle-style. But the grid is large (8x8), and when you find a word, the letters are removed from the grid, and the letters above them drop down a row, and new letters are added at the top. (Also, there's no timer; you can take as long as you want.)
And there are a bunch of elaborations—for example, the letter tiles are made of various materials, and a word must be made up only of one material. And you get "coins" that let you buy various special actions, like a bomb to remove tiles.
It all may turn out to be too complicated for my tastes in the end. But what I'm really liking about it right now is that you can strategically pick words that cause other tiles to fall into the right places to make some great words.
For example, I just arranged things to allow me to spell CASUISTRY, for 4,984 points, and I am mighty pleased with myself as a result.