Well I've never played Fortnite and Minecraft, and likely never will (not my type of games), and of the other two, I was a bit disappointed by GTA V, but IV was pretty good. I also liked The Witcher 3. I can't say any of them were as "relaxing" as one I played this summer during an extreme and stressful heatwave we were having, called Days Gone. It's just very unique and well done. The game world is beautiful, outdoorsy, and fun to ride the bike through, the enemies are immersive and quite often random and unexpected, and the sound is really good. My last play through I didn't sleep to travel in daytime like I used to, so I was often riding through dark forests and tunnels at night. Mind you as well, if you ride too close to a zombie that sees you coming, they can pounce on you and knock you off your bike, especially at night, when they are stronger and more aggressive.
This last play through I also played with a mod called Massive Hordes, which makes most of them MUCH larger, except for ones that are scripted as part of the campaign. At first I worried not sleeping would conflict with this and make things too hard. After all, if one zombie can knock you off your bike, imagine what 500 could do if you unexpectedly rode up on them. Then I realized you can use them like weapons against hostile camps. All you really have to do is maintain stealth (mainly stay quiet), alert an enemy with one of 3 types of oil can suppressors you can scavenge from abandoned cars, then watch the horde swallow them up as they loudly fire back at you. LOL
The game just uses some interesting concepts, like zombie hordes that roam, and hibernate collectively. Your bike is also a small armory of sorts you can store extra ammo on, and you have to be near it to save game. You can also upgrade it quite a bit and you have to if you want to get all the syringes in medical cold storage crates the game's federal emergency response teams leave behind (NERO - National Emergency Response Organization), because some of them you have to jump the bike over a big gap to get to. Syringes boost your Stamina (most important), Health capacity, and Focus (slows time when you take an aimed shot).
There are also several missions you do for one of the NERO scientists in exchange for him looking for your once assumed dead wife, including one that takes you deep into a dark cave to look for his missing team of 4 scientists. That is a very spooky mission. It's just very well done, and the story is engaging and immersive. There's no other zombie game quite like it, but as the devs say, it's not really just a zombie game.