This is the 'secret' but best link for seeing levels imh. There is no way to click to get there so to speak. You need the link.
(ps. Note that the win/loss for the OG levels is wrong, since number of attempts where not recorded before. Insane is on a completely different scale I think then any other 'official level'. However, I don't know which is hardest to gold. On insane you basically need to start in the right spots for gold thru. Also, they should use the old AI i guess, it's overall worse but might take some getting used too after playing prod 2.0 (current AI))
Edited 12/27/2018 20:07:58