There should be slightly different music for the different areas... also, the speedy boots are terrible - the only thing they are good for is getting some hard to reach gems. However, once you have them, they are too easily to accidentally use and make the boss fight harder when they go off when you don't want them to. I suggest setting them to the shift key so the player doesn't accidentally use them.
Oh, and once, the boss vanished and never came back, but I didn't win and I had to kill myself to leave (there was a patch on the map that caused damage - was this the boss?). You really need to fix that.
I can tell you put allot of time into this, but the only fun parts are the skill challenge and the offensive campaign.
Also, your game is hard to navigate - I didn't even KNOW there was a challenge mode the first play through.
 "Robot Wants Puppy"){kind=icon}
 "Cursed Treasure: Don't Touch My Gems!"){kind=icon}
 "Talesworth Adventure Ep. 1"){kind=icon}
 "Enough Plumbers"){kind=icon}
 "Maverick"){kind=icon}
 "Walkinator"){kind=icon}
 "I Can Hold My Breath Forever"){kind=icon}
 "SteamBirds"){kind=icon}
 "Imperfect Balance"){kind=icon}
 "Dead Frontier: Outbreak 2"){kind=icon}
 "Passage in 10 seconds"){kind=icon}
 "ImmorTall"){kind=icon}
 "Zombie Outbreak Simulator"){kind=icon}
 "Level Up!"){kind=icon}
 "The Gun Game"){kind=icon}