The most awesome thing ever shown on the DS screens.
Each level starts off with a charming manga-style situation presentation, involving the person or people that need help. Things go downhill awfully fast for these poor souls, and just when things look bleakest, they scream out in their most powerful voice, "OUENDAAAAAN!" This is when the fun starts.
The Ouendan leap out of nowhere, always ready and vigilant to cheer people on, by dancing to a certain song. Each level is accompanied by a song that you must dance to, and they're all awesome, head-banging, high-energy songs that will get you pumped up to dance! You dance in each song by tapping "hit markers" on the DS' touch screen to the beat of the song. In later levels and higher difficult settings, the markers get more frequent and faster, forcing you to concentrate extra hard. Also thrown into the mix are "phase markers", which are like normal hit markers, except you must hold down the tap, and follow them around until they stop. There is also the rarer "spin marker", where a plate appears on the screen that you must spin very fast in order to pass it; you can also get bonus points this way.
The song selection is excellent for the most part. If you like rock music, then you'll like Ouendan's music. In fact, I have put the game's entire soundtrack on my iPod, and I listen to it every morning! It's energizing, invigorating music, and it's a blast to listen to and play with.
Make no mistake, Ouendan is a hard game. I mean, really, REALLY hard. In the game, you must keep up a good score going in order to pass the level, as designated by a constantly-depleting energy bar. Also, the bar depletes even faster if you miss a note, forcing you to try even harder to keep your head above water. If the bar passes below the halfway point at the time of a stage's event intermission [a point in the song where you can see if your cheering has helped or hindered the person's performance], then the person will fail that portion. Also, the Ouendan will stop dancing until you get things going again; apt punishment for you sucking at that song. However, if you maintain the bar's level over the halfway point, the person will succeed. If you keep at it with enough practice, you can beat any song. And you'll feel quite victorious about it. In later difficulty settings, the bar depletes even faster, essentially forcing you to do better than great in order to survive.
All in all, Osu! Tatakae! Ouendan! deserves its place as one of the greatest rhythm games of all time. Plus, you won't have to spend $100+ on cheap plastic guitars and drum sets! That's certainly a good thing. So play Ouendan today, and get fired up over the power of the cheer squad!