Getting fatigued with games usually means you've lost a sense of investment.
Everyone plays games for different reasons: Experiencing new worlds, being challenged and overcoming said challenge, creating feelings of dominance, gradual progress, ect. This is going to very strongly define your taste in games. The thing is, just as a person's taste in foods can change as they get older, so can their taste in games. As others have said, you may need to try out new games, but the important bit is that you're going to need to drastically rethink the sorts of games that you enjoyed.
I went through a bit of a shift roughly three and a half years ago. I used to be more into "immersive" and "meaningful" games. I also liked things that were sandbox and open world. I liked the breadth of experiences that they provided and the sense of wonderment that I'd get, but I gradually found myself having a harder and harder time doing anything other than playing for half and hour and going "huh, neat idea I guess" before I had practically given up playing video games. I didn't really feel much of a reason to play.
What got me out of the rut was picking up Counter-Strike. I was absolutely atrocious at it, but when I saw people play well, I'd be driven to try and improve. Before long, I was invested and could play hours on end without even blinking. It wasn't really even "fun" in the traditional sense until I had gotten a thousand hours in and could start destroying people, but I never got bored playing it. These days, I've started to pick up Guilty Gear and Streetfighter as well as the Souls games and Bloodborne, games that make me feel like the hours I put into them translate into personal improvement. It's a great feeling. I've dabbled in more story driven experiences here and there, but I'm primarily driven by games with tons and tons of room to improve.
On that note, here is what I would suggest: think of the last three or four games that you really enjoyed, and then try to find something that heavily contrasts it. I could make suggestions, but it's all kind of dependent of what you used to enjoy.