Complex sentence: Jun Senoue re-arranged two of his tracks from the Genesis version for "Sonic Adventure" in 1998, explaining he included the tracks because he personally enjoyed them, but they had not widely been heard, as the Genesis version was not released in Japan.
Split into simpler sentences: Jun Senoue re-arranged two of his tracks from the Genesis version for "Sonic Adventure" in 1998. He stated he included those tracks because he personally enjoyed them, but they had not widely been heard, as the Genesis version was not released in Japan.