so here are my results (1695% in total) for comparing, so you can see in which level you could get more sliced away :D 1-100, 2-100, 3-100, 4-100, 5-92, 6-100, 7-100, 8-100, 9-100, 10-100, 11-100, 12-100, 13-100, 14-30, 15-59, 16-100, 17-33, 18-62, 19-62, 20-57
lvl 16 can be solved with 100 % with the method described by gomo psivarh, too. just cut a TINY slice from the top of the blue box, so it starts shaking. unfortunately i didn't see it falling, because it took some time and i was surfing in another tab :D
@TwistedClock: yep. i agree to boricua8319. first build up your radar, so you can see which side to defend next. don't waste time by deytroying boxes or opening chests. build up defence, everytime u have a little time to breathe. i prefer the carot (long range instant kill weapon) or the chilis (short range big area weapon).
@fearedjames: i just did level 1948 with 1 star. it's all about attracting the planes into your gas clouds. first of all the little planes by flying right. after killing them take care of the big one. i killed them all by gas, none of them by bullets. the bullets-only-plane of mine just helped attracting the enemys. good luck!
i also think, that cargo bridge is much more challenging an thrilling, but i beat cargo bridge some time ago. so this here is a good way too, to kill some time
 "3 Slices 2"){kind=icon}
 "3 Slices"){kind=icon}
 "Katwalk"){kind=icon}
 "ESCAPE"){kind=icon}
 "Granny Strikes Back"){kind=icon}
 "Solipskier"){kind=icon}
 "Miami Shark"){kind=icon}
 "SteamBirds"){kind=icon}
 "Robot Wants Kitty"){kind=icon}
 "Balloon in a Wasteland"){kind=icon}
 "City Smasher"){kind=icon}
 "BridgeCraft"){kind=icon}
 "Wake Up the Box"){kind=icon}
 "My it company"){kind=icon}