Actually, the way the made their game according to its engine(Unity of course), the game uses 2D assets to make it look like a 2D rendered game, but after I watched a video from Shesez, it’s quite clear that the devs are using Unity’s 3D engine, and that is what makes it harder to develop a new map, rather than make it just 2D. Do making 2D games in a 3D game engine isn’t like impossible or something, but it is still hard because you have to manage a lot of assets in 2D. So there, now you have the answer to why a new map can take too long to develop for a 2D(3D if you find yourself sure about it) game.