Official story and features:
"The main character in Odama is Yamanouchi Kagetora, the general credited with creating the Way of Ninten, a philosophy that puts the greater good above the individual’s needs. With this philosophy to guide him, he finds that his individual soldiers can band together to create a force strong enough to defeat even the most powerful enemy.
When his nemesis, a general named Kendare, kills his father, Kagetora exacts his revenge against a vast army with only 30 soldiers in his command. Kagetora has a secret weapon, however, a legendary weapon called the Odama.
The Odama itself is the most prominent character in the game. This gigantic ball rolls across the battlefield, pulverizing anything in its path - friend or foe. A commander stands guard between the two flippers, hacking down any soldiers who attempt to pass. The army of soldiers carries items for players and obeys their every order."
Story from Nintendo's site
"- Using giant flippers, players aim the giant Odama ball to bowl over enemies, shatter their defenses and wreak havoc on the battlefield.
- With the Nintendo GameCube Mic, players command men to charge the enemy, defend positions, seize the enemy gates and much more."
Features from Nintendo's site