Not sure if there's going to be a system in a future update or not for a rank better than gold as there are multiple levels you can get extra coins. Levels such as 16, 23, 41, 43, 45, 62, 64, 74, 78, 80.
Probably more though. Had a lot of fun messing around for these as well
Huh, I didn't really expect to have this much fun. Pretty enjoyable.
But lacking in the difficulty department for me, but after viewing through the the description and evaluating my experience, I can happily say that it did help me enjoy my day a bit more.
 "Economical"){kind=icon}
 "Arcandies"){kind=icon}
 "Bullet Heaven 2"){kind=icon}