Repost of my earlier suggestion from temp forum. You know what I am talking about: they are in most semi-advanced side-scroller "arcade" (in broad meaning) games: portal-shapen entities on the background. You, as a player, see them up front. When character enters one (usually by pressing "up" key), he teleports in some other place, to another portal-door usually. It could be other point of same map, or it could be interior of a building, et cetera. Screenshot below is taken from the old game called Zeliard, just to illustrate what I am talking about. Let's call backwall doors "portals". Nothing magical here, it's just a name to differ these doors from usual doors from Terraria, which are going into side walls, not in back wall. I will think and explain this idea in Terraria terms, because it's good common ground, very close to Starbound, closer than anything else. And now let's try to explain how I see it could work in game. You need artificial wall to put portal in it. Possibly it is even not any kind of artificial wall. Or maybe another layer is used to do what I am talking about in next point, just like one for wires. This blob of artificial wall (or zone marked by new wires-like special portal-layer stuff) basically IS whatever is inside the portal. It's the room. It's empty, and anything that is NOT an artificial wall connected to blob with portal corresponds only to unbreakable darkness. So, say you build a house 9x5, with background wall. You put a portal in this wall. You can enter this portal and you will be in "pocked dimension" which actually is just "another room in the house", exactly 9x5. Inner room / outer room, you get it. Inner room background wall is exactly similar to background of the house, but it can be changed without changing "outer" wall background. You can't remove inner wall completely, it works as an underground-cavern-underworld layer background wall, but it has default appearance corresponding to your outer wall in this place. If you are adding another floor to your house (in outer world; you can't make it larger from inside), making it 9x10, inner room enlarges accordingly. If you are breaking background wall from the outer world, you can destroy furniture and side walls (blocks) in inner world. They could either be destroyed completely or thrown to the inner/outer world. I don't really care, your call. Portals are hard to break for hostile mobs and environment. They are immune to explosives. Oh, or maybe it applies not to all portals but only to these ones crafted from tougher materials. Anyway, if portal gets broken, but background wall is not completely crumbled, then you can rebuild it at the same / near spot, regaining entrance to lost room. If you are trying to build a portal, and there is already a room on the other side, and your inner portal gets in the way of some furniture or blocks or whatever is there, it CAN be built, and stuff gets broken. This is less annoying than "blah-blah, you can't build there, useless log/stone/brick is in the way". This idea can work side-by side with few other suggestions brought by some people here on forums, at least on temp one. You probably saw them already, but I will include them here. Sadly, without pointing to persons who actually started these ideas, because I am too lazy to scan forums for them, but if anybody will provide links to original threads/posts with said ideas, I will gladly include them here. So, next two suggestions are not my own. /* Interiors of a building should be invisible from the outside. Various people post this suggestion. Backwall also duplicates as "front wall", making these non-transparent buildings look good. */ Adding to these two ideas: if you are using glass wall, constructing window on your back wall, this same window should appear on your front wall, and it could be semi-transparent, making interior of the house at least partially visible from the outside. In the end, purpose of this suggestion (and its' sister suggestions mentioned nearby) is, basically, to add more 3-dimensional feel to Starbound without making it actually 3d game. Mind you, I am far from being stupid enough to scream "waaah, Starbound/Terraria are 2d, therefore they suck", 2d is awesome in itself, always loved it and always will, it's great media. But still, in my opinion several layers are better than one flat surface. Also, Tiy said that developers don't really care about size of worlds, which is great: if you can handle infinity x 1 layer (okay, infinity x 2: blocks layer and backwall layer, background landscape image doesn't counts), then you probably can handle infinity x 4 (seems like 5: frontwall, blocks, backwall, inner room blocks, inner room backwall; but frontwall and backwall are identical, so it's more like 4). And you definitely can handle finite world x 4. In my opinion, infinite planets are redundant in infinite universe. It feels better just to have them "round" as in "you go to the right long enough — you return from left" of various sizes. Infinite world would never feels like home, it can't be reshapen into whatever player wants, and it just is not cozy.