There are three StreetPass games I've received "for free": Puzzle Swap, Find Mii I & II, and Market Crashers. For five years Puzzle Swap kept me using StreetPass Plaza even when I became bored of the other minigames. Then Nintendo messed witn Puzzle Swap making it waaay too easy to fill in a puzzle panel!! :( Now it looks like Market Crashers'll be number one on my list of free minigames.