In this contest, you have to make the story of the next Kingdom Rush game (is does not have to follow up Frontiers' ending) all you really need is a plotline of the game from start to finish, like this (since I'm making the contest, I wasn't going to enter this)
-A kingdom to the east of Linirea is attacking! you must protect Linirea and take the fight to them!
-Around three levels before the final level, it is revealed that the emperor of the kingdom of the east, has been overthrown by his evil adviser who is an alien in disguise/in cahoots with the aliens
-After defeating the aliens, the red crystal shatters, and assorted enemies from the past 2 games, take the pieces
-The kingdom of the east would be inspired by assorted East Asian cultures
-One of the terrians would be a Bamboo forest
-The enemies of most of the levels would be inspired by the warriors of assorted East Asian cultures (not just Japan, but also China, Korea and Mongolia)
-The enemies in the last few levels would be inspired by various fictional aliens, from Gamorreans http://starwars.wikia.com/wiki/Gamorrean to Arrowtongues http://aliens.wikia.com/wiki/Arrowtongue
You can add in stuff like the setting, characters (both good and bad) enemies and towers, but the main thing is a simple plotline of the game from beginning to end
PM me your ideas, I can't wait to see what you come up with (also, give your idea a name)