If you're extremely vigilant, you'll come across stamps in each level of Super Mario 3D World. These cute little illustrations can then be used on the gamepad when posting to Miiverse. Now even the least artistically inclined (like me) can make awesome little Mario-themed portraits.
Even for those that find every single stamp in every level, you'll notice that there are still five stamps missing from the collection to make it complete. Getting the last five will be a little more involved.
The last stamps are actually stamps of the five main playable characters, including Rosalina. To unlock them, you'll need to beat every single level as that particular character. For example, to unlock the Rosalina stamp, you'll need to beat every level in the game as Rosalina.
This should significantly raise your gameplay time.
