The game feels like a hybrid of Boggle and an inverted Tetris. Once you get used to using the mouse to click and drag through letters to form words and navigating with the keyboard, the interface becomes quite intuitive. There are power-ups in the form of other symbols: "!" creates a deep one-column-wide vertical shaft, ">" clears all the letters in the row that it is sitting on, "_" destroys a random set of tiles, "?" randomizes all the letters, and "*" takes out all letters in a 5-by-5 grid.
You don't necessarily need to activate the power-ups when you uncover them. I find that using the "?" power-up usually causes the resulting letters to be harder to make words out of. You also have the option of delaying usage of a power-up by guiding it down with you: for instance, standing next to the power-up and excavating under both yourself and it works nicely.
Once you finish a game, you get a report of various statistics about your performance. If you enable the "Internet" option in the Settings, the game will also report your scores to the central server and tell you how well you did compared to other players...
As of today, only 2% of the words on the word list had been found, according to the Lexcavator Twitter account. According to the developer's blog, the leaderboard is completely anonymous, so you don't have to worry about generating a login or a password or recovering a password when you've forgotten it. It's simple and done the right way, just like everything else about the game.
This is the kind of game that you will find yourself wanting to play repeatedly. There is also a Quest Mode which consists of a series of untimed challenges (like, find four 4-letter words, all in lines, without finding any other words).
You can get the game at lexcavator.com. It is being distributed on a pay-what-you-want model. I initially downloaded it for free, but I'm going to go back and pay for a copy to support the developer.