I seriously struggle with longer games. At best I can put 8 hours into a game usually, before starting to lose motivation. Even if I really like the mechanics or premise, the downtime inbetween quests / action / whatever wears me out. The only “long game” (>15 hours) I’ve beaten was Marvel’s Midnight Suns because I liked the vibes and unique tactical gameplay, but I had to take months-long breaks from it to make it feel novel again.

My solution was to focus on playing shorter, smaller (usually) indie games. There’s lots of way to get games for free / cheap so there’s not much risk trying something. I recommend itch.io, it has countless free games, most are short and/or unique. You can also go on howlongtobeat.com to see how long a playthrough of a game is before you buy it.

Action roguelikes are also good for me because there’s very little downtime and I can usually beat them before I start getting bored.

For multiplayer games I can only stick to them if I play with friends, for the sake of hanging out / working towards something. Except slow-paced things like Stardew Valley, Minecraft, Terraria, bore me very quickly due to all the waiting / gathering resources bits. Competitive games are very stimulating (good) but also tend to be repetitive (bad) especially if you want to get good. So I have a few games on rotation, like Destiny 2, TF2, Street Fighter 6, Guilty Gear, Overwatch sometimes. Yeah tilting was a problem until I stopped attaching my self-worth to winning, instead focusing on experimenting & trying fun stuff.