Obviously, no list of this sort is complete without the elephant in the room being addressed. We're talking about the official Fortnite Mobile game.
Fortnite Mobile is massively successful, even if I find it incredibly frustrating to try to build while fighting at the same time. If you don't have a PC to get in on the fun download Fortnite for iPhone or Android.
Soot anything and everything, find Llamas, buy skins, build up and try to survive. Fortnite takes the best of PUBG and combines exciting building mechanics almost like a more advanced Minecraft and blends it into one incredibly addicting game.
The game really needs no introduction of any kind. Remember, you can't get Fortnite for Android from the Play Store, and you gotta download it from Epic's website itself.
Also, try FortCraft. It's basically a complete ripoff of Fortnite, and it's loads of fun.