Hey, thanks a lot for dropping a review. I am pretty sure the lag is caused due to playing in browser and we will work on an updated version with all the bugs fixed and make it downloadable. As for the gun not working, it does not work in the tutorial for whatever reason but it works in the main game. We are working on fixing that and any other bugs that might turn up and release a newer version without any bugs. Really glad you liked the concept for our game!
PS: Half Dead looks really interesting.