Ken10Ben, levels 81 to 90 can be accessed from level 60. The portal for access is called "Platycodon" (not sure if it's spelled that way). Also, you can feel free to explore every part of the big levels (10, 20, 30, 40, 50, 60, 70, 80, 90, and 100) to see which realms (worlds) each big level can take you to.
best time 15:46, wow
Don't even try to play a older version even once: they are boring. Other then that, rating: Infinite/5.
That's a great game but... Where's the 81-90 levels? I found all but these. Levels I've been. 1-10,11-20,21-30,31-40,41-50,51-60,61-70,71-80,91-100. I found no 80s world. However, there is a fake exit on every huge level of three worlds that appear in the first huge level (10) which makes me think 80s were destroyed.