Terrain is one of those things that so far, hasn't been perfectly recreated in computer graphics. But it is almost there! Looking over a beautiful landscape can be one of the most amazing feelings in the world. And is probably my inspiration for these tutorials.
If you want to create a game like Sim City, or an RPG, then you are going to need some sort of tiling engine. This breaks up the ground into a bunch of known images and places them on runtim. This saves us having extremely large image files for an entire map and also makes it customizable in-game.
Lets face it, particles are ALOT of fun. Whether you want to create a weather system, some awesome fire, or just throw a million objects around randomly, they are both stimulating in a game, and fun.