Most games lose their appeal eventually and most games age poorly too. Not many I still would want to play after years/decades. The saddest for me is Age of Wonders, I used to play that over and over for many years. It never got boring for me because I used to like the comfy repetition and I got to try new stuff sometimes. It all had a sense of wonder -.- about it which was mostly because the maps seemed huge and I was such a noob that it took me forever to go through them. So I'd play that map for days until it was done and loved it. But when I play now it all feels so small and such a waste of time. There's not that much to do and not much in the game, most of what you are doing is chores of clicking ok on 20 things each turn. If you speeded it all up and cut out all the crap it would be 2 minutes. It just totally lost all interest to me suddenly. The battles are the best bit and for that I may as well play KOTC or something which is better and more focused on it. I also feel like my love for it in the past stopped me from questioning all the stuff that sucks about it. Now I see so much wrong with I rather just play something else.
I even saw a thread somewhere I think on the official forum saying what would you want to see in AOW4, and I couldn't even be bothered to post. I'm tired of the same games over and over and things that don't progress. Any game that has 'maps' that you play in, the chances are it's stupidly small and massively limiting. Every 10 years they increase by 50% or whatever so when you look back at an old game (especially an RTS) it's like playing in a world the size of a kitchen table. But even now it's kind of already dated if it even has maps at all. A lot of games like Tropico and RTS and stuff, I loved them in the 90s but they just haven't progressed at all since. And some things spoil me, like after being bothered by the claustrophobic 'maps' I was talking about, you play something with a semi-infinite world like Minecraft or whatever and it's hard to go back to such boxed in old games.
I think getting older makes you bored of the same old crap, and if gaming was good it would still provide plenty of interesting new stuff even for us. But it's so dead, so stagnant and rewards all the wrong shit. It is in a really bad way. My advice is try modding what you like until you can't play it anymore. Then move on to some other old game. I have some on rotation, STALKERs, Arma 3, Wizardry 8, SWAT 3, JA2, System Shocks, some old racing games and MMOs and stuff. There's not much keeping me a gamer though really. It's literally just that I know how good it was in the 90s, it's not nostalgia or whatever, it's because of how the business worked. I keep my gaming PC because I think it would be so easy to get back to that point, it really surprises me things are this bad.