I adore the concept and in general this game is really polished for a game jam!
It is really refresing experience not to play another puzzle game! this game has action mixed with some kind of tower defense (a genre that I LOVE).
The graphic and the style are well rounded and clear to understand.
I want to play more levels with MORE content in the near future! May be you could create towers or hechmen, night levels, a TUNNEL, explosives, alchohol, prison wagons, poker cards to collect, a shop/station between missions... I hope that you will continue to develope it!