On level 15 you should jump while walking left, hit the wall in mid-air (switching to the right), land on the high ground and jump again right before the ghost (that should be on the floor).
Survival mode must be really more challenging, and the lag must be fixed too. Collect bonus/coin with mouse is nice because it increases the difficult a little bit.
Fastest way to finish the dungeon: choose one flying character (better with more HP, I'm using bahamut) and fly all the way to the end of a level without kill any enemy.
SPOILER: Last level, what was the password for the hint "Luke 19.4. Last word." ?
I've powered every other pc and the game just ended without letting me power the last one...
 "Sleepy Knight"){kind=icon}
 "Reach the core"){kind=icon}
 "Pixelo"){kind=icon}
 "Achievement Unlocked 3"){kind=icon}
 "Auto-Smash!"){kind=icon}
 "Road Of Fury 2"){kind=icon}
 "Desktop TD Pro"){kind=icon}
 "Great Dungeon in the Sky"){kind=icon}
 "Mu Complex : Episode One"){kind=icon}
 "9"){kind=icon}
 "Pwong 2"){kind=icon}
 "Super Duck Punch!"){kind=icon}
 "Flight"){kind=icon}
 "Idle Mine"){kind=icon}
 "The Peacekeeper"){kind=icon}
 "ESCAPE"){kind=icon}
 "The Irritating Button 2"){kind=icon}
 "Red Remover"){kind=icon}