:You tend to start out with a low number of possible matches. This puts you on edge.
:Treacherous. You can go from having several options to being out of luck in just a couple of turns.
:Appropriately well-guarded. Easy to exhaust your choices.
:The beginner's level, for the most part.
If you hadn't guessed, the mahjongg games they bundle with the computer are addictive. I'm weaning myself off to get some productivity back.