Outstanding work for a game jam. The attention to detail and game feel is impressive, specially the overall behaviour of the explosions and particle systems. I particularly enjoyed the slow motion mechanic when shooting the agents, it's just incredibly satisfying. The main menu idea is also pretty clever.
The aesthetics and audio are really well suited for the casual feel of the game. The music doesn't feel annoying or repetitive at any given point, and I believe that's because the attention is at the most part being drawn by the audio of the explosions.
My only two suggestions would be to implement some sort of shop to be able to spend the earned currency. I'd be more than willing to spend some coins so that I could select my first weapon beforehand, for example. The second one would be to release the game on mobile platforms, seriously.
Amazing work, guys. Congratulations.