patent for game mechanics

What I don't understand is why? You want to protect the valuable aspects so whether it is UX (trade dress), characters/storyline (copyright) or gaming engine (trade secrets on server-side) why are the mechanics so important that it is worthwhile spending up to 6 figures on getting patents around the world. Not only that, you have to set aside a legal fund to chase infringers or pay for patent insurance. So, have you done the cost-benefits? Or is an ex-employee more likely to split and set up a competing game rather than a random chinese clone emerging? I suggest you sit down and do a basic risk-analysis = probability x potential loss. One you rank them, you can figure out how to mitigate, manage or throw money at each.

You can patent the methods used by the inner workings of your gaming app. Assuming it is software only (not novel new hardware you invented), it must be novel and non-obvious.

Your source code is, of course, copyrightable