The hardest song to play on guitar is subjective, as it depends on the skill level of the guitar player. However, some guitarists consider “Eruption” by Van Halen to be one of the most challenging songs due to its fast and intricate guitar riffs. Other difficult songs include “Through the Fire and Flames” by DragonForce, “Tenderness” by Dan Lenahan, and “Celestial Bow” by John Petrucci. It’s important to note that what might be hard for one player may not be as challenging for another, so it’s best to start with beginner-friendly songs and gradually move on to more complicated pieces.