Open Geometry dash -> get 10 silver user coins -> go to settings -> click the lock(right upside)
-> ????? -> Profit!

• Oh no...
  
• Thief!
  
• Thief! Thief!
  
• Decrypter
  
• The Unknown
  
• The Unseen
  
• Catch them all!(unknownness)
  
• Nice shot!(unknownness)
  
• Revealing...
  
• Third eye open...
  
• Very Clever...

+ 30/8/2015 'Catch them all!' and 'Nice shot!' is get bug, so I don't know that is killing player or not, probably it will fix soon. ROBERTOP!

Type this passwords and press black guy(guide's head image). you will get secret icons.

Oh no...-password:lenny (cube)
Thief!-password:sparky (coin)
Thief! Thief!-password:spooky (cube)
Decrypter-password:blockbite (UFO)
The Unknown-password:robotop (robot)
The Unseen-password:ahead (wave)
Catch them all!(unknownness)-destroy WI-FI icon in main. (icon)
Nice shot!(unknownness)-destroy 2.0 sneak peek 1 icon in main.(icon)
Revealing...-password:mule (ship)
Third eye open...-password:neverending (UFO)
Very clever...-password:gandalfpotter (Trail)
+ IN 2.0.1
Nothing is hidden-password:your nickname (icon)
Doomed us all!-password:type 8 - 16 - 30 - 32 - 46 - 84 (wave)
Thanks for Miner_Zack673 !
By...SuperPizzaLuigi's youtube, Zobros's youtube

If you know unknownness icon's password, tell me what is that password!

(i'm not american, so i'm not good at English,)

Thanks for reading!