Smule has released Leaf Trombone: World Stage, its latest massively multiplayer online (MMO) musical game for the iPhone and iPod touch. The game provides users with a simulated Trombone and tools for composing and publishing songs. Players can perform their song live to a global audience, and then receive ratings from self-appointed judges. Songs can be rated on a scale from 1 to 10, or judges can send messages and emoticons for detailed critiques. Following each performance, the evaluation is added to the player’s standings and the current rank is updated.

The app also provides a self tutorial for beginners, with a music box that accompanies the player and shows leaves that float toward the correct notes. To play the instrument, users must blow onto the iPhone mic, or use a touch mode on the iPod, and then slide a finger to change the tone.

Once users become familiarized with the instrument, they can become judges to review compositions from others. The app provides an interface for listening to live performances, along with a library of user-created melodies.

Leaf Trombone: World Stage is now available from the App Store for $1.