Simplicity. Sometimes a simplistic concept can be an amazing one. Take this game for example. A Space Shooter for 2 Bucks! takes the shoot 'em up genre and doesn't try to clone geometry wars, doesn't try to make a next-gen Galaga, and doesn't try to innovate the genre with some fancy new gimmick. It just took everything you would expect a shooter to be and put it into one pretty little package. A $2 package that's worth every penny.