Terrain Overgoes
sand to rocks to grass to dirt and back again
'Terrain Overgo': The overlapping between two terrain tiles. Each terrain tile has an overlapping texture, though sometimes, as with dirt tiles, it is extremely crude looking.
During the tutorial, the whole 'terrain overgo' issue will be addressed, almost just touching on the surface, for
2 main tilesets, which I see as crucial to one's 'survival'. These two are Ashenvale & Sunken Ruins, using a combination of tiles from each tileset. You won't really require anything, as it is all theoretical, guided by some pictures, but the point of this is to teach you about it. A lot of people simply jumbled in their tiles one after the other, heeding no warning about the fact that these tiles are overgoing onto each other horribly.
Note - Overgoes are decided by
Advanced -> Edit Tileset
[edit tileset window with the current arrangement.]
Example: 
In this example,
5 tiles are used -
Village Rocks, Ashenvale Grass, Lumpy Grass, Dirty Grass and
Sunken Ruins Sand. This is the order of the tiles in the Edit Tileset screen - you can see it too. The Sand overlaps anything, using an extremely smooth, sandy texture. You can't see it, but sand goes over dirty grass in the same way. If dirty grass was above sand, dirty grass would be 'above' sand in the same way it is above grass, lumpy grass and rocks.
Sand and dirty grass are excellent intermediate tiles, because of their extremely smooth and good-looking overgo, without any noticeable texture. The first texture you can see is the one of lumpy grass - a yellowish, quite sharp zigzag along the other tile. Though at times, this can look bad, it often adds to realism and an overgrown look.
Often, the factor of good looking or bad looking depends on the tile which the other one is going into. For example, lumpy grass going over onto rocks and grass looks alright, even good, but going onto Sunken Ruins/Ashenvale dirt - not so much. This is mainly because of the contrasting colours. Since it doesn't look good, intermediate tiles are used - like sand & dirty grass.
Grass's overgo is an outcrop of slightly brighter colours than previously. It, like lumpy grass, looks bad in combination with dirt and similar tiles. The only tile in this image which it goes, rock, looks fine with it. However, in too large amounts, it can look bad again. Small amounts against dirt, sometimes simply corners touching (which creates a smaller overgo) achieves a quite nice overgrown effect of wilderness.
In the example image, the overgoes are done well (in my book), however, if grass were to be added, right on top of the other tiles, this would happen:
In other words, an extremely undesirable effect. The overgo is sudden, contrasting and very ugly in general. Dirt should ALWAYS be at the very left end of the tiles, with rough dirt right beside it. Rough dirt, when above other tiles, other than dirt, has an overgo exactly the same as normal dirt: while the tile is rough dirt, the overgo is dirt.
Other Tiles: I have not talked about every single tile: some of them I simply never use, or don't see as 'worthy' of being used, others simply didn't fit in without doodads. Ashenvale Leaves, usually above dirty grass, is a tile that can go over everything with a smooth overgo. It is another intermediate tile, and usually used near trees. Vines, which I barely ever use, have an overgo which can go partially smoothly over anything, dirty grass and leaves should be above them, and the overgo shouldn't be overused. All types of rocks are usually in the center of the bar, either left or right of any grasses; depending on your preference.
Other types of Grassy Dirt are used much the same as dirty grass, though a bit less prominently, because of their 'thin' appearance. Road tiles (such as large bricks/small bricks of Sunken Ruins) should be below grass on country roads and above grass in city roads - or depending on the state of the roads how you want it. When multiple types of grass are used, the darker should be on top, or the one with the more overgrown overgo.
Though this only touches on the surface, and a bit below it, of the whole topic, I do hope the guide is helpful for you. I see terrain overgoes as a crucial part of a terrain. Thanks for reading.
