I know how to unlock all Bonus Levels the easiest way (So far) Get all ten artifact pieces 
that make up each one fron any eight levels in the game. Then you will need characters with 
the academic ability, explosion ability, excavate ability super jump ability, thugge chant 
ability and tiny size. Then put the treasure chests on the green squares and smash what you 
made then pick up the key and in the artifact room open the passages.