The game would make more sense, if the weapons were so big and bulky that they had to be supported by a tripod on the ground. Thus, they would only be able to shoot in a certain direction. It seems to me that it would also go with the "We have no real weapons, we have to make them out of big, expensive building materials"
Found out how i did it, If you have a touchpad, if you let go immediately while having a unit selected and about to be placed for the first time, the unit will drop where you let it go.
If that makes any sense at all.
Make sure to find a good flying character. It will help you find the secret hiding places that are on nearly every map and kill characters like: Genie, basilisk, and the Dragon Knight. (most of these have like 80 hp)
 "Flight"){kind=icon}
 "Desert Moon"){kind=icon}
 "Last Egg Alive"){kind=icon}
 "Neon Race"){kind=icon}
 "Great Dungeon in the Sky"){kind=icon}
 "Contour"){kind=icon}
 "All We need is Brain"){kind=icon}
 "Gravitee Wars"){kind=icon}
 "Lucky Tower"){kind=icon}
 "Wizard's Run"){kind=icon}
 "Mastermind: World Conquerer"){kind=icon}
 "Garden Gnome Carnage"){kind=icon}
 "Up Down Ready"){kind=icon}