This is a common thread and question that I've seen pop up all over the internet since I first joined message boards in the early 00s. It's you and I dont mean that in a judgmental way, but it sounds like you're probably burned out or being brought down by other factors in your life.
I said it in 2002 on gamefaqs, I said it in 2005 on my small local game message board, I said it in 2010 on reddit, and I'll say it again. The best time for gaming is now. Because there are still good games coming out regardless of the bad contemporary trends, and the indy revolution of the 10s has only made that more true. On top of that all the classics you know and love are still behind us and playable.
I think you need to take a step back and try to figure out exactly what it is about gaming that you used to enjoy and try to figure out why you may not be enjoying games anymore. It could be the type of game youre playing, it could be that you're just burned out, and it could be external factors in life.
Did you used to play games with friends and family that have drifted apart as you got older? Does work leave you drained and with little time and energy to play your long playsession single player experience? Is the game that you're playing one with a toxic community? Do you feel unfulfilled in other parts of your life and feel guilty that instead of working on that you're engagin in your hobby? Are you experiencing other mental health issues like depression or anxiety that might be tinting your enjoyment of things?
There are a number of reasons you might fall into and out of gaming. I'm in my 30s and I personally go through seasons and times when I play a lot of games and when I focus my hobbys on something else. Ive felt like "maybe I'll never get that immersive feeling again like I did at 18" a bunch of times in my life and then picked up games I couldnt put down. Once you find out the why you can try and tackle the problem.