I had a 20% coupon for the local games store. I didn't really need any miniatures or RPGs they carried, so I decided to look for family games. I bought Carcassone on the recommendation of my friends, but it was listed for both 8 and 10 years or older, and both ages are older than my kids. The manager showed me Blokus. Lay down funky shapes and try to play them all? Sounds lame. But...it did have a Mensa award and the German "Spiel des Jahres" award, pretty high praise, I thought, so I bought it.
It's a big hit at the house with the kids! It's listed for five and older, but my son, who is about three months short of five, picked it up in no time and was competitive in his first game. In fact, we've played four games so far, and he's come in second three times, beating his six year old sister. He asked to play it twice yesterday. Here's a three way game we played. I was red, him blue, and her green.
The rules, examples, scoring and variants take up both sides of a single piece of paper. Basically, you must cover the small square in your corner with the first piece you play, and every subsequent piece must touch at least one other piece of your color at a corner, but may not touch any piece of your color at an edge. Try to play all your pieces.
Update: Heh. I now see that if I had played the 1x1 block, which I'm pretty sure was the last block I played, in the gap of the U shaped piece on the left, I could have played my final piece along the left side!