The first scene you see in Song Summoner involves a guy named Ziggy and his brother Zero getting cornered by a couple of big robots. A conductor comes and saves the day, but only after Zero was captured by the robots. Five years pass and Ziggy is now a conductor with musical abilities allowing him to create 'tune troopers' who are created from songs and will fight with him in his battles. With his training complete, he sets off to rescue his brother.
Song Summoner is a very unique game due to its core concept of using the songs on your iPod to create 'Tune Troopers' who will fight with you in battle. Each song you have will make a different trooper with different stats, and this causes for a lot of experimentation. Your troopers will have a class of bronze, silver, gold, or platinum and a rank of D, C, B, A, or S, and they will also have one of a few jobs such as a Knight or Monk.
After each battle, you will get points to award to your troopers. You use these to upgrade them to the next level (i.e. bronze to silver). This will significantly upgrade their stats and give them new abilities.
However, a Tune Trooper won't last forever. Every time you use one in a battle, it takes a use off of them and they only have a certain amount of these until they can't be used any more. Thankfully you can just go back to a hip-o-drome and make more troopers, so you never really run out.
Song Summoner plays much like Final Fantasy Tactics. You have a grid with all fighters on it and you take turns between your units and your enemies. It's a turn based strategy game also much like Fire Emblem. Certain jobs have advantages over other jobs and different units have different attack ranges and abilities.
A unique feature the game has is that when you listen to the songs your troopers are based on when not playing the game, your groove meter will go up the next time you play it. The more your groove meter is filled, the more points you get. These points can be used in battle and can help you significantly.