At the end of the day,  you are the parent. You are in charge, and you make the rules.  Use this power with care.  I’ve seen many parents use the nuclear option - not just for games, but for anything. 

You get what you want, and you can injure your relationship with your kid.

Am I saying let your kid do what they want to, whenever they want to? No. I am saying create reasonable rules, ofter positive alternatives, and create clear and flexible structure.  Computer games can be bad, sure - but almost anything can be when taken into extreme or used maliciously.