According to this thread: http://tieba.baidu.com/p/4152831918?pn=2
g小调瓶子 is the author of this composition, based on Prelude and Fugue in C minor, BWV 847. Since it is now known, it turns out the game most likely has to soon properly credit him/her.
Although, with the author's name already written at the top-right corner of the piece, I don't think it is likely for Piano Tiles 2 developers to mistaken this composition as "Unknown". The same goes for "Penguin's Game", which the band name is known, GELATO.
Link to scores:
Author's baidu profile: http://tieba.baidu.com/home/main?un=g%E5%B0%8F%E8%B0%83%E7%93%B6%E5%AD%90&fr=pb&ie=utf-8 (Chinese)