Handheld games, even "hardcore" ones, aren't nearly as frontloaded as console titles. People tend to pick handheld titles up more when they've finished with their current one, or need one for a trip or something. I know I'm going to buy Chinatown Wars at some point, but I'm not really playing my DS too much at the moment, so it's in more of a queue.
Note NSMB and MKDS. Excluding Japan, (where NSMB did start off with a bang) they got good, but not spectacular openings, but keep on going like an energizer bunny on viagra.










