I've recently been at work trying to put together a reasonably complete set of 16x16 fantasy RPG tiles.  This is a massive undertaking to say the least, and as such, it's important that I avoid making mistakes that will cost me a lot of time and energy.  While there are a lot of excellent pixel art and tile making tutorials out there, I have yet to run into one that addresses the topic of planning a tile set.  Like many others, I've learned that it's possible (in fact, very easy) to design a tile set in such a way that it's overly complicated or (worse yet) useless for making any real maps.  This article will hopefully help you to avoid that particular eventuality when designing your own tile sets.

Starting out Simple

The simplest tileset of all requires little if any planning.  I'm referring in this case to the sorts of tilesets that are commonly used with Roguelike games -- each type of terrain gets one single tile, without regard to what might be adjacent to said tile.  Tile maps of this type are symbolic in nature, in that they generally don't attempt to paint a believable scene.  Rather, they simply represent what's going on in the game.  These types of map tiles are worth mentioning here because they're a good starting point.  Any tile game engine can handle them, and they're a quick way to build game maps while you're working on your engine.  They can always be improved or replaced later if you're looking for something a little more flashy.

Adding Depth

One problem with simple "roguelike" tilesets is that they don't give you any feeling of being in a three-dimensional space.  Sure, ultimately most tile-maps are two-dimensional in nature, but you can add a sense of immersion by "faking" a third dimension.  Instead of viewing things from directly above, we move the camera down a bit and look at them from a 3/4 perspective, which allows you to show the height of objects.  It isn't really three-dimensional, per se, but in making this transition, you've just opened up a new can of worms -- specifically, you now need to create wall tiles in addition to floor tiles.  Now, we're still assuming that you want your terrain to be perfectly sqaure.  This isn't particularly realistic, but it remains easy to do, so it's a good place to start.

With wall tiles, there are a couple of things to consider.  Now that you're presenting the illusion of height, do you want your character to be able to walk "behind" those walls?  Are your walls going to be a tile thick, or are they just going to sit on the borders between tiles instead?  Keeping your walls a tile thick requires very little in the way of planning, and is the way to go if you're trying to produce something as quickly as possible. 

However, since this article is about planning a tileset, as opposed to how to avoid planning a tileset, we'll explore the other option.