Looks good so far, but I´d suggest to create a big version of the gun for the interface-gfx/guns folder and to change the sparks gfx for the little flames and stuff to a green color as yours are yellow on the screen. Try to use not only one color on the shell, you could use a dark grey for the low 2 pixels so it looks more like a shell. With some improvements this will be good for hide and seek