Yes, I noticed that issue a while ago. Unfortunately, I've moved on from updating this tool after deciding that this style of tile wasn't right for my project. That's why I uploaded the godot project: The problem is that the pixel math places the right edge of the previous tile on the same x coordinate as the left edge of the new tile, instead of one pixel over. If you're invested in using the tool, editing some padding between the tiles into the Draw script (by including a padding value in the equations that determine the size of the Viewport, and the starting point of each tile) should be doable.