It's pretty rare these days that I get excited about a videogame - but if you have a kid who likes Lego, then I highly recommend this sandbox, open-ended gem, Minecraft. Here's what I like about it:

Engages the imagination for building amazing structures in a straight forward way

Truly frightening for kids (and adults) - without being gruesome like say a Doom III or similar - We have a no blood rule for games - and there is none

Don't tell the kid, but it's kind of edutainment- learning about areas and volumes, crafting complex machines from simple ones, forges, flint and steels etc.

laugh out load funny. Because of the open ended world, absurd things happen. We had a similar incident to this fire building exercise below:

It was build by one extremely talented programmer , Markus Persson (Notch), and not a big software house like EA. I loved paying him for this.

It's written in Java, which normally I wouldn't care for, but this is the first Java game that's actually impressed me, works well in the browser, Windows and Mac.

Gameplay is first, graphics second. I like that it's blocky.

Here's a fanmade trailer

I discovered MineCraft through the Sift - thanks bunches