One of the best flash games I've played in a while. It was funny, well-paced, and designed so that no one weapon was the end-all of enemies. Personally, I found the gas lost its value after you put some money into the mines, but that's just my preference. This was an excellent game and I hope to see more from you in the future!
On a side note, there seems to be a glitch with the stun mines. It displays an increasing percentage underneath the mine that goes on until it detonates, at which point it resets and begins counting again. I'm not sure what it means or if there's a limit (I'm pretty sure my got over a 1000% at one point), but just thought you should know. Good luck!