Creating a new Unity project for our CCG
The first thing we are going to do is to download and install Unity Hub from here. Unity Hub is a desktop application that acts like an entry point for all Unity-related matters on your machine (projects, installed versions of the engine, licenses, etc.). It is much more convenient than manually handling all the different versions of the engine that may be installed on your machine at any point in time and is, in fact, the only supported way to launch the engine starting with Unity 2019.
Once you have downloaded and installed Unity Hub, create a new, empty project using Unity 2019.4.0 LTS.
Choose a descriptive name for your project and select the 2D template.
The next step is to add the Entities package via the Package Manager (make sure to select the Show preview packages option in the Advanced menu).
Finally, download the free DOTween asset from the Asset Store and import it into your project (which you can do via the Package Manager as well). Make sure you perform the additional setup step that DOTween requires by selecting the Setup DOTween option in the Tools/Demigiant/DOTween Utility Panel menu.
We will use DOTween for all the tweens/animations in our game. In that regard, it is one of the most well-known, performant libraries available for Unity.
Before moving forward, make sure to enable the Enter Play Mode Options (Experimental) setting in your Project Settings/Editor (available from the Edit menu). It is a good idea to enable it in all your new projects, as it will make entering Play mode blazingly fast, which will help improve your iteration times significantly.
With our project correctly set up (you should have no errors in the console at this point), we are ready to go!