There are 2 methods:

#1: use Bluestacks if you don't have much knowledges of virtualization and Android.
#2: use Genymotion if you have knowledges about Virtualbox, downloading APK, customizing virtual devices.
Method 1:Bluestacks
Go to Bluestacks.com
Download the version depending of your OS ( Windows, MacOS)
Install it
Connect your Google's account
Search for the game in the search bar
Install it and play

Method 2: Genymotion
Go to Genymotion.com
Go in Ressources then Fun zone
Click on "Download…"
Register
Download your version for your OS ( Windows, Mac,

Install it
Now, go to virtualbox.org
Install it
Then launch Genymotion
Click on add, choose the Android version (for me, i prefer 5.0)
Choose the ram's quantity, number of cores... in preferences
After that, launch your virtual device
Go in web browser
Go to apkpure.com
Search for Theotown
Download it and Install it
ENJOY

