Super Mario Galaxy is the most pure fun I've ever had playing a video game. It's a masterpiece of level design, play mechanics, and art direction. If you haven't played it yet, I strongly encourage you to get your hands on the game as soon as possible.
If you don't own a Wii, buy one to play this game. It's that good. If you can't find a Wii, hijack a Wal-Mart truck, grab a Wii, bury it, get arrested, pay your bail, dig up the Wii, go home, and play this game while you await your trial. It will be worth it.
One of the unique design features of Super Mario Galaxy is its cooperative simultaneous play, dubbed Co-Star mode by creator Shigeru Miyamoto. Player 1 performs all the platforming, enemy bashing, and coin-collecting; while Player 2 collects star bits, stuns enemies, and generally functions as Player 1's assistant.
Nintendo has been trying to figure out how to create a compelling auxiliary player mode for over 10 years, beginning with Kirby Super Star for the SNES (AKA Kirby's Fun Pack in Europe). That game featured the addition of a "helper," which was an enemy-turned-friend that could be controlled by a 2nd player using a separate controller. It was an interesting, if not completely successful, experiment, and Miyamoto discovered that cooperative simultaneous play was a greater challenge than he expected:
Friendly two-player play is something that’s easier said than done. It’s not a problem in competitive play where the two players are equal, but in scrolling games where one player is the main player, the question of whether the other player could really enjoy the game was just one long-term challenge. With those games, it always seems like the second player is being forced to play, and at times it’s not much fun.
As good as SMG is, I was initially skeptical about its co-op mode. It sounded gimmicky to me, and I couldn't understand why anyone would want to be Player 2. Now that the Thanksgiving family crush has ended, I finally see the light. Single-player SMG is great fun, but playing with a helper is even better, especially if that helper is a young child or a person curious but intimidated by video games.
I completed the Fountain Galaxies with my mother-in-law, and it was a blast. She played without fear of losing or impeding my progress. I focused on navigating and progressing (and a little showing off), and we explored the indelibly wonderful galaxies together. When she got distracted ("I just like looking around," she says), it was no big deal. When she got tired, she dropped out, and I continued.
What truly surprised me was how much fun I had being Player 2 when she decided to give it a go as Player 1. As she wandered around learning how to move Mario, I kept the Goombas at bay. When she became disoriented I could point at a bridge or a pipe with my Wiimote and suggest she try going there. I have loved making Mario jump for 25 years, but it turns out it's a lot of fun helping someone else discover that little piece of joy for herself.
Super Mario Galaxy's co-op mode will never be confused with Gears of War, but there's much to be said for synchronous gameplay that allows players of different skill levels to play together by design without handicapping, ala Guitar Hero. SMG provides two very different styles of play, rather than the usual "easy," "hard," "expert" modes, and it's a design choice that works remarkably well.
Now I want to see other games implement their own versions of Co-Star mode. I can easily envision a racing game, for example, in which the primary player steers, brakes, and generally races the car - while the co-op player functions as pit crew chief, monitoring the vehicle's condition, calculating fuel, and scheduling pit stops. There must be other genres that could benefit as well.
I realize SMG's version of co-op isn't for everyone, especially hardcore gamers. But Co-Star mode is a valuable and innovative step forward--one that makes an instant classic like Super Mario Galaxy accessible while sacrificing none of its challenge. I hope we see more of it in games to come.