For people who get angry at the sideways levels, do Ctrl+Alt+right arrow on windows and it will change the angle of the screen Ctrl+Alt+up arrow to go back
This is just a small tip, (this doesn't seem to work with 4x1's) If your being squashed and have no exit, try Corner flipping, it saved me there more than once! :)
because it is completely normal for a PAPER airplane to have flaming rocket boosters and not combust into fire as well as turn into a hedgehog every time it hits the ground.
this is a link to the expansion to bloons tower defense 4 wher there is a 1 click speed up http://ninjakiwi.com/Games/Tower-Defense/Play/Bloons-Tower-Defense-4-Expansion.html
please click + plus so people know about BTD4 expansion