I've also become addicted to the brain training game on the DS. I got it for my kids but got sucked in. For years my math-enthusiast friend has been trying to get me into sudokus (and crosswords too) but has been met by supreme indifference. I've never had much patience for brain-teasers. Unless there's a point to it, I can't motivate myself.
That game however, with its graphs and rankings and stuff has given me a motive: competition!
I did my first ever sudoku last week, it was one of the basic ones and I did it in about 9 minutes. I've got it down to about 6 or 7 now and I'm getting bored of them.
Must be an ENT thing. My father took up sudoku, figured out how you played it and then put it down... objective achieved apparently.