It seems like grass would randomly be growing everywhere. Wouldn't it be better if it spread like in terraria? So first you search for dirt blocks with already grown grass and then search all the dirt blocks around it and add grass to those. Would it be possible to read the map.png and find all the grass blocks here instead of searching (at the beginning of the game)? Then each grass block can be added to a list or something which is checked every few seconds and if those blocks have no grass, they are removed from the list. If they do have grass then you search all surrounding dirt blocks. If there is a nearby dirt block that has nothing on top, then grass is grown on it, and that new grass block is also added to the list. Or maybe this could be done client side and it can be one of the tick box things in settings so people can choose whether they want it on or not.