For devices that have a Home Button:

1. Press your Home button twice quickly.
   
2. All your open apps will be displayed. Swipe left or right to locate Two Dots.
   
3. Swipe up on the app's preview image to close the game.
   
4. Return to the Home screen and open Two Dots.

For devices that don’t have a Home Button:

1. From the Home screen, swipe up from the bottom of the screen and pause slightly in the middle.
   
2. Swipe right or left to find the app that you want to close.
   
3. Swipe up on the app's preview to close the app.