He has quite a high libido and I know my lack of interest has taken a toll on him, and he's told me he feels unwanted a lot of the time. However, when he's staring at his monitor 12 hours of the day, only to say a couple words to me every hour or so, I honestly feel no drive to have sex at all.

That is absolutely no wonder. This guy is (perhaps unknowingly) treating you like a live-in sex object. He doesn't pay you any attention when you're home together except when he's feeling horny and wants to have sex. Your immediate response should be to point out that deciding to take a break from gaming just to have sex isn't exactly the pinnacle of romance in your mind.

Then you move on to talking about your needs, and your relationship's needs, and how you can ensure both are being met. Make a plan together to dedicate time solely for one another outside of video games. Instead of reddit, maybe you two go out for dinner or watch a movie at home together and cuddle. Or here's a shocker, maybe you sit and talk to each other with no external stimuli for a short time each day. Once you both start reconnecting mentally and emotionally, the physical side of a relationship suddenly starts working naturally again. If he wants to have that with you, he should put in the time and energy first.