While most role-playing games are rooted within well-established fantasy or sci-fi worlds, Eternal Sonata takes place within famed composer Frederic Chopin's dreams -- his innermost thoughts during the final three hours of his life in 1849. The result is an unusual tale that explores the ongoing struggle between the light and the dark. In Chopin's imagination, an alternate universe exists where characters tirelessly fight to cure a terminal illness. Players initially guide a young girl named Polka, her boyfriend Allegretto, and a child named Beat across forests, villages, and other outdoor locales, battling monsters and meeting new friends along the way.
The combat system is a blend of turn-based and real-time movement, with characters alternating turns yet performing melee, ranged, and magic-based attacks in real time. Light and dark also influence each encounter in dramatic ways. Special moves are available for characters standing in sunlit areas, for example, while enemies are deadlier when lurking within the shadows. In traditional RPG fashion, defeating creatures will award experience points to improve attributes such as health, defense, and speed. Within each area are a number of chests to find, each offering helpful items to use in combat. Chopin's final dreams are brought to vivid life through the developer's use of cel-shaded graphics, anime-styled characters, and the musician's famous works as the score.