Little Game... Big Bang....
As a casual gamer, it takes something special for me to take out my DS and play it in my spare time. Big Bang Mini is just that game. Ever increasing difficulty combined with strange flying animals and battling snowmen make this a niche game that everyone can enjoy. It's easy to pick up and play.
The whole game is played with the stylus and the occasional use of the L and R buttons. Shooting with the stylus is very intuitive and easy to do. It's kind of a cross between a puzzle game and a shooting game.
If you are a fan of the very clever niche games that are all over the DS catalog, I highly recommend this. And for $20, you get a lot of enjoyment for a little bit of money... :)