Super Paper Mario is a Platform/role-playing video game developed by Intelligent Systems, a division of Nintendo. It was originally set for release on the Nintendo GameCube but then it was released for the Wii. It is similar to the previous two Paper Mario titles and the Super Mario Bros. for the Famicom / Nintendo Entertainment System (NES). The game will combine side-scrolling 2D gameplay with free roaming 3D graphics and to a somewhat lesser extent, RPG elements. – [info from Wikipedia]
Also to note that in the Wii version the 8-bit sprites are in their original colors from the NES, but the Gamecube version had them in “modern” colors. Thanks to Cubivore10 for the contribution!