Firstly I think there should be a possibility to make underground bases/bunkers that would add more possibilities to make an base than just having it on the ground and to keep it balanced you would need to find a way to get air inside of the base/bunker
Secondly
I think there should be more depth to buildables such as elevators,moving platforms,openable roofs etc this would open up a huge load of possibilities for making bases
I mean, making bases is caves would be pretty nice, especially being able to build in a cave without excessive effort or F6 edit mode, but I think digging into the ground would be a bit hard to implement.
Not sure how I feel about this;
On one hand, making bunkers would require editable terrain which could easily be abused, but if it used an elevator that could take you up and down levels, it might interfere with the map.
However, on the other, it can create secret hideouts which would be cool 
More indepth building is confirmed, and I believe items like opening roofs and moving platforms are planned as they will certainly aid in the automation of things.
Hmm what do you mean by easily abused like getting under the map?
That could potentially be one, but I was more leaning towards players digging moats around the spawn and trapping new players.
Don’t get me wrong, it sounds like a nice idea, but I’m not sure how it could be feasibly balanced, and this would also require a different type of terrain that Nelson may or may not want.
To balance trapping perhaps doing something similar to 3.0’s too near to spawn thing but on a larger radius
I’d be worried about players destroying certain parts of the map because there is no limit to editing terrain.
Hmmmm thats also an issue yeah the balancing is truly a problem perhaps having something similar to a hole what you can place as a floor where you can start digging and have a certain radius like 3x3
That might work, but maybe it should be like a claim flag, in that you can only place one, but within that location, you can edit the terrain as you see fit. (So long as it’s not concrete or cement)
As I said previously, this would be nice but editable terrain is something Nelson would have to consider and would most likely cause a major decrease in performance.
The performance indeed is an issue maybe if there would be a option when lets say the player has covered the area up so it wont render
I’m not sure how performance will be handled in UII, this may or may not work.
true guess we have to wait and see
A solution could probably be that you can place objects under (as in say you put a floor under the terrain), and the terrian inside it disappears, like the landscape holes in the devkit for 3.0. When it is destroyed/removed, everything inside of it (including players) dies.
Maybe the Master Building Tool could be a placeable item, that claims an area, and allows the player to design and create foundations, tunnels, and frameworks of buildings.
That could certainly work, so long as a player can only place one on the map at any given time.
i like it but what if a troll makes a endless pit around the spawn, so nobody can get off the “Too near spawn area” ?
Nah there should be a limit how deep you can dig
There definitely needs to be limitations on how far you can dig.
There should be a substantial protected area around spawn locations.
Just as buildings decaying in 3.X helps prevent that, holes refilling would help prevent that in 4.X. (I think some people have some very strong opinions on how exactly building decay needs to be tweaked for 4.X, or what it cannot be changed to, so I’ll just leave it at that.)
I think a good idea in my opinion is not being able to dig anywhere at any depth, but have certain hills or mounds that you can dig up but there is a set amount of depth that you can dig, plus this could open up certain easter egg possibilities. And elevators and such I have been thinking about a lot and i think it’s a good idea.
I like the idea about elevators is really good and if they had other building objects that moved like elevators or maybe escalators/ski lifts. I think it would add a good layer to the game.