As a gamer that loves Dungeons and Dragons I played through Neverwinter Nights 1 and found that they included a toolset which also included multiplayer. NWScript looked similar to C/C++ and was very powerful. I started learning it and was hooked. Made a Middle Earth module that has been copied many times and modified from the NWVault. That lasted roughly nine years then tried Neverwinter Nights 2…which had a better toolset and easier coding but so many things that needed to be worked around to get to work that worked perfectly in NWN1. NWN1 needed a graphics update…and I am going to do it! 
I found nothing except Unity3D really to at least attempt to replace the NWN1 Toolset…which is what I want to design. Interiors 10m x 10m snap together to form interesting dungeons, houses, castles…whatever. With Unity3D it had basically NOTHING included. So Pro Grids and Pro Builder and Playmaker and…Blah Blah Blah…purchase from the Asset Store. Then making each work together! Gawds this makes me sick up! Then you get everything working together…install the latest Updates from each/any dev’s assets and now something is broken again! Ask a dev a question and receive no answer or perhaps the standard answer being ‘Read the Docs’…which…Are NOT Updated for THIS UPDATE! Gawds! Not to mention the Asset Store can be really random quality with coding related assets…requiring more code fixing!
So now I have been working in UE4 and it simply works. Almost everything is included…I certainly miss NGUI though! I have been transferring NWScript coding into Blueprints and all is working perfectly (BPs take awhile to make)…and I have not coded any C++. At this point I am positive that having a NWN1 style toolset envisioned in UE4 is very very possible. I am certain there will be something that does not function but when it happens with you lot and Epic’s amazing helpers will have something in mind for it.
It is absolutely striking how very different the approach to this is between Unity and UE4. I also very much love all the polish in the UE4 interface as well…Unity is simply…blah. I get all this UE4 for 20 US?
One last example. Using World Machine and making a heightmap to import into each UE4 and Unity3D is much simpler in UE4. Plop in the colour map on top of it and start painting veggies in UE4. In Unity3D I need TerrainComposer and RTPv3 to make an equivalent quality map. Even though they are both super amazing they take a lot of time to get the colours to overlay properly and shaders to work properly. Not to mention if you are using the Free Unity then you will be missing a lot.
Edit Update:
Since working in UE4 and Unity side by side I am on the fence and leaning towards Unity. For all the polish of the UE4 UI and the code source once I got past that part the sparkles dulled. Blueprints are much improved over Playmaker but takes so bloody long to be productive. So switching to C++ to take care of things is like pulling teeth with the ridiculously slow Visual Studio. Then in UE4 the Compiling Shaders…gawds!..every time you change ONE PIN or PARAMETER…Compiling Shaders. Give us a Compile Button! I guess I have been spoiled with how quickly NWN 1 & 2 (NWScript) and Unity (Mono) code and compile. Then there the materials…very complex things can be done with them…which is very nice…but doing something seemingly simple like Diffuse, Normal Map, AO, Specularity from textures yields terrible results. No No…you MUST multiply this and that added to that then combine these 4 textures THEN plug it into Colour. F’ing really? So much for that.
UE4 is a very nice engine but I shall pass on it. Especially since my personal Unity has all the necessary assets to make it a complete engine.