You don’t have to understand Japanese to be able to have fun while surrounded with it. Just do whatever you want, and then ask yourself “can I do this activity with just a little more japanese?”
It doesn’t have to be much. If you take a break from Japanese by playing games, take two minutes to change the interface to japanese. For those games you love, you probably know the interface inside and out so even if the characters are unintelligible right now, you can still navigate your way around without problem. And yet, it give you one more change to glance at japanese and recognise words you’ve just learned in WaniKani.
I’ve changed all of my browsers and youtube to Japanese. Most of the time, I don’t really notice the difference, but sometimes I need to navigate the options, and I’m forced to read a few kanas to find of the options I need. The first time I used a VPN, I got locked out of all my Google accounts due to security, and I had to recover my credentials while my interface was all in Japanese. I didn’t understand much, but one パスワード here, another メールアドレス there and a 番号コード at the end, and I recovered everything without any english. It was really satisfying, even though I wasn’t able to read any kanji at the time.
Personally, I’m not much of a gamer; I prefer to read fanfics. So I grab the fanfics I like, put them in deepL, and then try to read 2-3 paragraphs in Japanese before rewarding myself with the full chapter in english. I don’t look up every word, just those patterns I notice through repetition.
What I’m trying to say is that most people have an instinctive grasp of what is fun or not. It’s just a matter of being aware of your own likes and to keep finding ways to do those things with a little more japanese.