TumbleWords is the first game created by lumoludo, who are Mike Arlington, and Jen Pelham. It's a really fun word game, where you have to create words by chaining together the blocks. As words are created, the tiles are cleared, with new ones falling into place, and the stacks collapsing together.
It's a game mechanic you've probably seen before, only with matching colors instead of making words. But it works equally well with words too. If you get really stuck, hit Shuffle to get some new letters.