Multi-Level construction.

[Spartanbeast]

So, I had an idea that would enable the construction of different levels.
This could enable Bunkers, underground storage, Defense towers and many other creative Ideas. It would allow the user to not use as much space due to lower levels of a base, or upper levels of a base. There would be a max limit to the number of levels. But this would be a great tool to build underground bases. Add onto the idea, it would be awesome if this was implemented.

[Geertje123]

This has been suggested a lot of times before, and maybe it will come, but probably not any time soon. Adding a new dimension to the game would need a lot of rewriting of the code.

[Playbahnosh]

Z-levels have been requested countless times, mostly because it's a logical addition to the game. But it's much harder to implement than most people think. Terrain generation, pathing AI, the graphics engine, the combat system and basically everything else has to be completely rewritten to accommodate the new dimension. New physics engine for gravity and effects on pawns, objects, projectiles, etc. Revamp combat and cover mechanics for vertical line-of-sight. Not to mention extending the existing weather and temperature system for Z-levels... and fluid dynamics is not even in the game yet. Many people bring up Dwarf Fortress "that game has Z-levels no problem", and that's true, because DF was designed from the ground up with Z-levels in mind (mining is what dorfs do). Rimworld is using Unity for a baseline 2D engine. And while theoretically could be modified to include a sort of fake-3D with multiple 2D layers, the implications of Z-levels are way more far-reaching than most people can imagine. Basically you have to rewrite almost the entire game to do it.

[Professor Cupcake]

Z-levels have been requested countless times, mostly because it's a logical addition to the game. But it's much harder to implement than most people think. Terrain generation, pathing AI, the graphics engine, the combat system and basically everything else has to be completely rewritten to accommodate the new dimension. New physics engine for gravity and effects on pawns, objects, projectiles, etc. Revamp combat and cover mechanics for vertical line-of-sight. Not to mention extending the existing weather and temperature system for Z-levels... and fluid dynamics is not even in the game yet. Many people bring up Dwarf Fortress "that game has Z-levels no problem", and that's true, because DF was designed from the ground up with Z-levels in mind (mining is what dorfs do). Rimworld is using Unity for a baseline 2D engine. And while theoretically could be modified to include a sort of fake-3D with multiple 2D layers, the implications of Z-levels are way more far-reaching than most people can imagine. Basically you have to rewrite almost the entire game to do it.

And to continue the point here, the performance would decrease at a geometric rate. It's bad enough already with larger colonies; until serious optimisations are made, Z-levels cannot be a thing.