How about adding and Audible Invite Alert for game invites. So often an invite is missed because it's just not noticed in time and if your multitasking it can be missed-all-together. The alert could be in the form of a chime, or some other noninvasive sound that repeats every ten or fifteen seconds.
There should also be an option for individuals to disable/turn off the alert if they so choose and a variety of tones to select from would also be very nice.
Phil