There is no character more associated with Wii games than Mario. Super Mario Galaxy 2 is for the Wii console and it based around guiding Mario through different planets, which are all different sizes and have different 3D landscapes. All of the normal Mario world extras are in there, including costumes, power-ups, and many other similarities to the original Super Mario Galaxy.
In a seemingly familiar Mario story, the game begins with Mario traveling to see Peach. However, before he is able to reach her, a UFO takes Peach (and in fact the whole castle) off the planet. Mario has to give chase, as he tries to rescue peach.
The great thing about the game is that each galaxy contains different worlds, all with different laws of physics. As you are solving many of the puzzles in the game, you are able to walk around all over the place without restriction. But this also means that controlling Mario isn’t always simple and it’s easy to attempt to jump one way and have the strange gravity pull you away somewhere else (although this can be part of the fun).
Mario can also take on a number of costumes, with each costume giving him a different power. For example, the bee costume from the original game is available, which allows Mario to fly around and climb on certain parts of wall. Each costume is usually specific and useful in the world in which it is available. This means that getting it can give you a big advantage on the level you are on.
Mario can also ride Yoshi, who is able to take on different powers by eating various items, including fruit. These powers, as you would expect from a Mario game, include things such as speed boost.
When it comes to Wii accessories, the main one for this game is simply the remote, which is used control Mario. By moving the remote in different ways you can initiate a different movement or attack from Mario. For example, by shaking the remote, Mario will usually commence his spin attack.
In general, if you enjoyed the original galaxy game and Wii games in general, Super Mario Galaxy 2 is a very worthwhile purchase.