About the mute issue, you should be able to mute only your browser (probably depends on you system though). You just right-click the volume icon, click open mixer, look for the browsers icon in the list and mute that. Other than that pretty good game.
One thing that I would like to see added, if it isn't to much trouble; weapon descriptions in the shop. I know it doesn't take all that long to read the description in-game, but it still takes up time and makes me feel like I have to rush more.
 "Survival Lab"){kind=icon}
 "Gravitee Wars"){kind=icon}