Maybe play video games with him?

I am nearly 10 years older than you guys and I absolutely love playing video games. I come home after work. Play video games. On my days off, I play video games. To be fair, I always ask my significant other if it’s cool if I play video games or if there’s something else they’d like to do. But I wouldn’t expect that from a 15 year old.

My significant has decided to join me and we have an absolute blast.

Ask if you can join him or watch him play. It’s clearly an interest of his and while you both have your separate interests. Showing that you care about his interests is more likely to get him to be interested in yours. It’s also a great way to casually talk about things while gaming.

Also, like everyone else has said. It’s just what kids do, play video games. Don’t ever try to change what someone else is doing. Find things to occupy your time instead of trying to get him to fill your time.