Among the 3DS's built-in software is a pair of strange little titles utilising the console's Street Pass function - Street Pass Quest and Street Pass Puzzle.
3DS Focus reports Street Pass Quest is a turn based strategy RPG to assist your Mii in escaping a mysterious tower.
Your three-strong party is culled from your collected Mii's - those of other 3DS players your console has automatically collected in passing. Or a cat in armour, for those who stay home all day and have some game coins to spare.
Reports suggest the game may last 30 or so levels.
Street Pass Puzzle is apparently allows the player to construct 3D puzzles with pieces collected from Street Pass connections.