Yeah, it does look menacing. But you're not offsetting the tileset - you just replacing the tiles, right? You see its still actually much more efficient to have several squares of tileBackgrounds, and switch between them, then having engine to redraw each of the tiledBackgrounds of water created from the tileset. Because for more complex map structures (not square) you can end up with 5, 6 or more tiled background instances for even one small lake, having it to be redraw every few seconds, where my proposition only needs as many instances as there is frames. Even in your example, all water is using 5 instances of tiled backgrounds already, where if you would do it my way, you would only need 3 :)