"Sherlock", a logic game for the PC
In Sherlock, you are presented with a 6 by 6 array of tiles. Each row has a different type of tile (faces, houses, numbers, fruits, and letters), and each row is scrambled. Initially, most tiles show tiny pictures of the six possibilities for that spot, and you have to figure out what that tile must be. To do that, you are given a bunch of rules, or clues.
There are several sorts of rules: This tile must (or must not) be in the same column as that tile; this tile must be (or must not) be in an adjacent column to that tile; this tile must be left of that tile; this tile must be in two columns away from that tile, while a third tile must (or must not) be in the middle column; this tile is here. (This last is the exception in the previous pp; this sort of clue shows as a "given" entry in the six by six array.)
You proceed by first doing all the easy and obvious deductions: If this must be in between those, it can't be on the outsides; if this must be left of that, it can't be on the rightmost column; if this must be in the same column as that, then it can't (or must) be here; and so on. As you proceed, you find that having eliminated this, you can eliminate that. Sooner or later, if you haven't made any mistakes, you know what all 36 tiles must be.
Imho, this is very good practice in sustained reasoning. The nice, easy to use GUI always shows you where you are (you can arrange the clues in any order you like, and can even move "used up" clues to (and from) an alternate page, so they don't distract you) yet you have to be right in (just about) every decision, or you will land yourself in a contradiction.
This game has been a big hit in our house. At five-nearly-six, Sam started by doing them with a parent (it can be very distracting to be told "Oh, this!" and "Then, that!" when you're trying to follow a logic chain of your own) but quickly got to the point where he's faster than his Dad, if not his Mom. (It's very frustrating to be the stupidest person in the house, at times.)
Sherlock is shareware (the author asks for all of $15) and requires an EGA/VGA and a mouse. The new Windows version ($19 + $2 shipping) is just the same, but looks a lot better and has sound support. Both are available directly from the author
Everett Kaseror, of course, off the net, at http://www.kaser.com.