Unity is a very powerful and versatile game engine. It is available in both Indie (free) and Pro (paid) versions. In case you haven't installed Unity yet, this recipe will show you how to do it.
Getting ready...
You will need Internet access to follow this recipe.
Locate and click the Download button, placed in the top-right corner.
Now, on the Download page, click the button to get the latest version of Unity. Wait for the download to complete.
Run the Installer. This is a very straightforward process that will install everything you need in a couple of minutes.
Once the software is installed, run Unity. That should take you to the activation dialog where you can choose between activating Unity Pro (provided you have a valid serial number), Unity Free, or a 30-day trial of Unity Pro:
Select your choice and click OK. You should be prompted to log in or create an account.
Register (if necessary) and log in to activate your copy of Unity and start using it right away.
There's more...
You can expand Unity's capabilities and reach new audiences by adding more platforms to your editor.
Acquiring new licenses
iOS and Android exporters are now included free, and others can be bought from the Unity Store at https://store.unity3d.com.