Would complex set pieces with unique features be possible to make?

[XirmiX]

From what I've seen of current set pieces, U&A's shop keeper and Two Worlds in adventure mode this would be doable. But the question is how complex it would be? So say I wanted to create a set piece that spawns in a certain prefab (a mob with just one animation specific for the set piece and then it despawns) when I approad a certain item from the setpiece (approach, as in get close to it on a certain radius, for r example 5 metres or closer). Would this be doable? And how complex could set pieces or other parts of the game could get? Like at the beginning of the game or at the beginning of adventure mode levels Maxwell giving his speech.

[Heavenfall]

The sky's the limit here, I think. There's very little not directly related to the 3d engine that can't be altered.

[Mobbstar]

If you want setpieces without specific arrangement or prefabs, I recommend making mini-biomes. It works well for me, as long as you don't shove them all into the same room-task (room-task means: It's a bit complex, indeed).