Moody 10 year old son and video games?

My usually happy, creative, and very smart 10 year-old son has become so incredibly moody over the past year with a serious addiction to his hand-held video game. His mood for the entire day is colored by whether or not he's being allowed to play the game. If he's not, look out. The whole house is colored grey by his depressed demeanor. He has very little interests outside of the game, although we insist he does a handful of extra-curricular activities. But no real passion for anything else that we've seen.. He's passing on play dates with friends if these dates will infringe upon his video game time. Despite my many best attempts with discussingg the situation with him reasonably(the more grumpy you are over this game, the more his dad and I will be putting limits on it, etc), his behavior isn't changing at all, as I don't believe he has control over his emotions like I just wish he did! During prolonged breaks from video gaming, I feel like I finally get my son back, and we are so tempted to get rid of the device for good because of this. But at the same time, I know he loves it. It is such a source of both joy and frustruation for him. I just don't see this as healthy for him. Evilness wrapped in black plastic! Help! Any advice??