The rules of Sudoku are quite simple. In order to complete the puzzle, you must fill each square with a number between 1 and 9 such that every row, column and 3x3 box on the board contains the numbers 1 through 9. Stated another way, you must fill each square such that no number appears twice in the same row, column, or 3x3 box.So now that we've got that cleared up, how does it play? Mostly, like you'd expect. Rather than writing numbers into the grid, you can use the keyboard and type them in, or click on the square, and a handy-dandy numeric keypad pops up in the square, allowing you to select the number you want without using the keyboard (and also allowing you to clear a square of a number you'd previously inputted).
This is basically another logic puzzle, so you know already I'm not too into it, but it's also such a simple game at its heart, that there's not much to say about how it's implemented. The ability to do everything with the keyboard, and alternately do everything with the mouse, probably adds accessibility for the handicapped and lets you play however you're most comfortable. Outside of that, there's nothing remarkable about the mechanics or gameplay.
While it may be more 'natural' to play the game on a piece of paper, playing it on the PC does come with its privileges. The game will let you know if you've screwed up by turning all conflicting numbers a nice bright red. It also has a nifty highlighting feature that points out all the squares that will be affected by whatever square is currently activated. Most amusing (and most morally questionable) are the 'Fill' and 'Fill all squares' commands. The 'Fill' command puts the logically necessary number in the activated square, if there is one, and the 'Fill all squares' does the same thing for the entire board. At the 'Easy' difficulty-setting, it tends to just solve the whole puzzle with the click of a button.
Your little book of Sudoku puzzles certainly can't do that but, really, what's the point of playing if you're going to cheat? Mind you, I would ask "What's the point of playing?" and ignore the question of cheating, but I imagine that anyone really into this type of game would not particularly care to use those features. Nice to have a safety-net though, I guess.
Another triumph for Linux, mostly. If it's your cup of tea, you'll find the leaves were hand-selected and perfectly dried, to finally be steeped in water that had been taken just to the cusp of boiling without actually hitting the boiling point, making for the best possible cup of Sudoku tea. I totally broke that metaphor, didn't I? It works, it has extra features, and yes, it will blend.