I've been using Dear ImGUI so far, but it doesn't have a reskinning option, so i think it's not that good if you want to ship your product, and doing some research i end up mostly with outdated libraries or ImGUI

So, what y'all use to create your game GUI / What you think it's the best anything to create one with DX11?

10 hours ago, Hodgman said:

It's another IMGUI library, similar but quite different to Dear ImGui. 

Would you care to very briefly describe what's the main difference(s) between Nuklear and Dear ImGui?

Nuklear is pretty much skinnable.
Dear ImGui has skinning options, but they are quite limited.

Doing everything from scratch on top of the engine's own 2D draw calls is the only way to fine tune the usability and get exactly the look you want. It's only a few lines of abstract component classes to make your own system and then you're not limited by any framework. This is my IDE's GUI rendered with my Direct3D 11 graphics engine.

On 8/9/2019 at 5:02 PM, ongamex92 said:

Nuklear is pretty much skinnable.
Dear ImGui has skinning options, but they are quite limited.

While Nuklear has some skinning options, one thing is take into account is whether it goes to point that is satisfactory for the needs of your game.

Dear ImGui is less skinnable but arguably has more ui features, e.g. drag and drop api, tab bars, docking, gamepad controls and some keyboard controls, support for extracting windows as native OS/platform windows, a larger community of users and widgets, etc. and upcoming ones: automation, tables. Whereas Nuklear appears stagnant by now (vurtun moved on to something else?).

My personal answer to the OP is that neither Dear ImGui nor Nuklear are designed for high quality in-game UI and you are better off writing your own. Game UI are very custom and simpler to write than productivity/tooling UI.