Its Fun. There aren't any Bugs I could find, but I found it weird that units needed to be close together to swap properly. Not adjacent mind you, I'd have understood that, but just kinda close?
The Unit Sprites are Great, but they don't fit the map aesthetic. Apart from this, I think this only kinda needs a coherent story to drag you through levels, instead of just a level picking screen, aswell as more units, especially enemies, and more maps obviously.
Main Menu Font is a bit hard to read, and endless mode doesn't really get more difficult the longer it goes on once the first Jumbo is down.