Hey there, thanks. I guess yeah, this is made with LT terrain generator or something like that, but generally speaking you take a heightmap that tiles seamlessly. You'll work with 2x2 copies of it. When the player eg. passes Z 0.5 of size the terrain, you reset him to -0.5, which looks exactly the same. And do that on the X axis too. Player won't notice the change of location. Given FX and NPCs etc are repositioned as well, accordingly.