React JS

What are drawbacks of using React JS?

First of all many devs switch to ReactJS because of the many advantages it has compared to other UI frameworks. It is hard to make out the disadvantages, because there are many advantages that come with them. I will name the following:

It is a UI library only. As such when building something with React you will have to include other libraries to handle other parts of an application, such as application state.
When comparing it to a monolithic framework such as AngularJS, you will find that there is no predefined way to structure your app (such as services, controllers & views in Angular). This means that it is the responsibility of the developer to find his/her own ways to effectively manage several parts of the application without a predefined structure. This can lead to significant overhead and long development times when the devised structure is bad or ineffective.
To avoid these pitfalls, it is not enough to just learn React and start coding. If you want to avoid trouble in the long run you have to research popular & effective ways to structure your app from third parties, such as blogs or example apps from github. Those however are rarely detailed enough to represent a complex application and as such can’t give you a good guideline on what to do and not to do. You will have to make your own experiences here and learn from them.
All the stuff going on in the background. React is mainly written using JSX & ES6, transpiled using Babel and build & packaged using Webpack & npm. Those tools are requirements to be effective when using React, however their inner workings & processes are not easy to learn and require significant time to understand. On the other hand if you skip learning those things, your build might fail with error messages that have no meaning to you and you will be stuck with code that doesn’t work and you have no power to correct by yourself.
React is still very young. The ecosystem behind it (open-source libraries, components) is still small compared to older frameworks such as Angular. You will not always find what you are looking for in open-source contributions.
Touching on the last point, while React’s APIs are mostly stable, there are still some things that can change in future versions (such as the childContext API). There is no guarantee that the code you write today will work with future versions of React.
Last but not least, it features a radically different approach to UI design by introducing reusable components. The process of learing how to think in React can be difficult for you if you have extensive experience using other methods, such as MVC. You basically have to avoid falling back into old thought patterns because they most likely don’t work effectively with React.

React js framework collections only offer a visual of how the UI will seem and relate, but they also stretch you more inspired liberty in the development.

Well, it’s easy to use and it provides less coding in creating a dynamic web application. It’s SEO friendly and has a very rich JavaScript library.

How about for game developers? How do they execute a code for a free strategy game?

The high pace of development: Developers not feeling comfortable with the high pace of development because of the constantly changing the environment. Developers need to be updated and learn new ways of doing things.

Poor documentation: It is an updating technology which stimulates so fast that there is no time to make a proper documentation. Developers have to write instructions on their own and for many of the manuals are difficult to understand.

JSX as a barrier: It’s a syntax extension which makes the scripting easy with the help of JavaScript but Developers find it difficult because of its complexity in the learning curve.

ReactJS Covers only the UI Layers of the app and nothing else.