Dabble

Dabble is a modern-looking and smooth-running, Electron-based piece of software that aims to provide you with a distraction-free and unified environment for writing novels, on both Windows and macOS.
Before we go further, please take into account that, at the time this review was written, Dabble was in a fairly young, Beta development stage, which means that it lacked some, very important features, which will be discussed more towards the end.

Modern and straightforward app for writing novels

Starting with the good points, we can point out the app's simple installation and stylish interface. The layout is quite intuitive, so even beginners will have no problems working with the app, and the transition effects between menus do a great job of reminding you that this is a modern app. While we're on the subject of neat effects, we would like to point out that, as you type, all the UI elements fade out, thus greatly improving your focus.
As expected, your novels can be easily structured into parts, chapters and scenes. The app allows you to add a wide array of useful notes, such as plot notes, character notes, and world-related notes. You can also be sure that you will swiftly find everything you're looking for thanks to its built-in search feature.

Under construction...

Having said this, we have no choice but to point out some of the app's (temporary, or at least we hope so) shortcomings. Export capabilities, account management, and cloud storage, as well as sync capabilities between multiple devices, are currently in the works, as the developer mentions on the app's official website. Furthermore, plotting and character tools, as well as support for Markup, are also planned.
Having said these, you should be a bit wary and make sure that you backup your work. Before we conclude, since feedback is a constructive part of the development process of any app, we would like to propose a few future features, namely integration with the most popular social media environments.

With a bit more development time, it will sure have the potential to become a  noteworthy app for novel writing

All in all, Dabble is still very limited and, in its current state, it's hard to see how it could become 'a thing' among the community of writers but its foundation is quite solid and, with a few more improvements and some added features, it might turn out to be a very good app for novelists, indeed.