Aura Cascade is an example of emergent design/gameplay. Basically the developer gives you a bunch of low-level tools and says, look, see what you can do with this.
This can be amazing in terms of creativity, but requires a lot of foresight to ensure it doesn't get out of hand. If done right, the dev is always going to end up surprised at what people can accomplish. While I have no particular preference for or against aura cascade itself, I genuinely respect the thought that went into the mod.
The Endergenic Generator mentioned above is another excellent example.
@Reika's reactors in ReC are a decent example as well.
Edit: not sure why I felt it was necessary to page reika there... I think I just always do when I mention his name so I'm not talking about him behind his back
This can be amazing in terms of creativity, but requires a lot of foresight to ensure it doesn't get out of hand. If done right, the dev is always going to end up surprised at what people can accomplish. While I have no particular preference for or against aura cascade itself, I genuinely respect the thought that went into the mod.
The Endergenic Generator mentioned above is another excellent example.
@Reika's reactors in ReC are a decent example as well.
Edit: not sure why I felt it was necessary to page reika there... I think I just always do when I mention his name so I'm not talking about him behind his back