With Nintendo expected to have some difficulty selling its Wii U this holiday season, one saving grace for the company is, and always has been, that the iconic Super Mario franchise remains exclusive to the Japanese gaming company.

Super Mario 3D World is an impressive reminder that Nintendo can still make impressive video games. The game takes approximately 15 hours to finish and IGN considers it to "pulse with vibrant and unrestrained creative energy." While many die-hard Mario players probably made their way to the end of the game quickly, it's possible they missed some of the more subtle winks to the franchise along the way. Below is a list of some of the top charming set pieces from the new game, courtesy of IGN.

Water Levels: Taking Mario underwater has become a bit of a joke in the fan community as often times everyone claims to hate the perfunctory swimming level. In Super Mario 3D World, the animation adds some fun to the adventure by having Mario and company puff out their cheeks when holding their breath. In addition, the music takes on a different more hollow sound as it reverberates through the water. It's a simple touch that doesn't do much to quiet water level opposition, but it's those small attention to details to that can keep things interesting.

Hidden Exits: Secret areas are a common staple in the Super Mario Bros. games. The newest title is no different. A secret hidden in World 1-2 can help you bypass the first world completely. A later one well allow you to do the same with the fourth world by dropping you through a pipe directly into World 5. For a look at where to find these hidden travel pipes you can find them HERE, via IGN.

The Year of Luigi: Nintendo has made 2013 "The Year of Luigi" by putting him at the center of DLC, games and even giving him his own train line in Chicago. In "Super Mario 3D World," the tall green-clad sidekick has several 8-bit sprites in sections of the game as little Easter eggs. Some are more obvious than others but when you find them they're a nice treat for fans.

For a more complete list of these hidden gems, including videos and how-tos, you can find them HERE via IGN.