Geometry Dash: Step to Hell by LaZye! (EXTREME DEMON)
AHHH YES FINALLY!!! This is the longest a level has ever taken me to complete, being like 1 month and a few days. The thing is, I wasn't demotivated to play this at all. In fact, I would be playing this for ~3 hours a day, every day up until I got sick. Anyways, I certainly hope this doesn't happen with the rest of the levels I will try and beat, because I've got some pretty hard ones planned... ;)
I am also the third to beat this o_O