Here is an overview of the game, via its store pages:

About

Soundfall is a dungeon crawler that combines looter-shooter action with rhythm-based gameplay. Venture out solo or with up to four friends locally or online. Collect loot and time your actions to the beat to become all powerful. Robust Campaign Mode, Free Play over 100 songs, or import your own music.

Key Features

• Play to the Beat – Soundfall is a fast-paced music-based dungeon crawler that combines looter-shooter action with rhythm-based gameplay to create a world of music unlike any other. The closer you time your actions to the rhythm of the soundtrack, the more powerful you become.
• Thousands of Loot Combinations – Unlock powerful new abilities, and explore Symphonia to discover incredible music-based weaponry. Customize your loadout with more than 500 pieces of equipment to choose from.
• Up to Four-Player Co-Op – Defend Symphonia with your friends, either locally or through online co-op.
• Import your Own Music (PC Only) – Import your favorite music to create incredible new levels within Symphonia.
• Five Characters to Choose From – Play as one of five unique musical geniuses, each with their own play style, weapon and special abilities.
• Explore the World of Music – Explore ten dynamically different environments and restore harmony to Symphonia.
• Defend Symphonia – You are a Guardian of Harmony—a musical genius transported to the world of Symphonia by the Composers to battle the forces of Discord. Together with up to four other players, you will fight your way through the corrupted Timbrelands of Symphonia, eradicating the Discordians and restoring Harmony to the environment.

Watch a new trailer below. View a new set of screenshots at the gallery.