Spweef was originally just a small testing ground for my coding ideas. Soon, I realized that I wanted to make a mod that didn't add any blocks or mobs or things of that nature, but instead I wanted to make a mod that made changes that were not noticeable at first.
Spweef adds ways to turn sandstone back into sand, gravel into cobblestone, and even make chain mail and end portal frames all within the bounds of vanilla Minecraft.