Since the Blue Blur's debut in 1991, Sonic the Hedgehog has built up a solid fan base and game library. However the games may have performed critically and commercially, it's safe to say that the music accompanying them is consistently of a high standard. Throughout Sonic's history, fans have been treated to a diverse array of music, from hard-rock, bossa nova and electro-pop, to thrilling orchestral and vocal songs. SEGA has consistently collaborated with mainline music groups, and also has an in-house band, Crush 40, who are very popular among the fan base.