Complex sentence: Tony has done a few tracks for the series of games known as Sonic the Hedgehog, his first time doing such tracks was on the soundtrack of Sonic Adventure released in 1999 by SEGA.
Split into simpler sentences: Tony has done a few tracks for the Sonic the Hedgehog video game series. His first track for the series was on the soundtrack of Sonic Adventure released in 1999 by SEGA.