Pulling the trigger is annoying. I thought I would just click it but I realized I had to pull it back. As for cocking the gun, it just seems unnatural. So, overall, the game is rough around the edges and needs some work.
This has a lot of potential. But it needs to be made harder, longer, have more options(like level editor and such)and better art direction(background art, tile art, etc.)
Tip: Send a few custom troops out, then send villagers. Once you get enough money, guild a cannon. Repeat this a bit but you may need to hire a lot of custom troops.