Maybe this is a stupid noob question, but I have been playing for a little while, I have broken 750K and made it to level 48, but I have yet to locate any keys except for that first one.
Is there a guide available on how to get keys and opne up some more doors?
after you finish the game. You will be able to play nightmare mode (the fruits start angry and the fireball comes faster) and you will get 
and 
on levels 50 and 103. You can get 
as a normal item in the game, 
in the parallel dimension in lvl 55, 
in the end of parallel dimension 46 and with it you can go in parallel dimension in level 15 and get 
in the end. There are a few more but you don't have to worry about the keys before you start reaching levels 80 or so 
. They are not easy to take.
