This may be more likely to happen on a tablet rather than a laptop or PC.
You may have an early generation tablet and you may have other apps/pages open at the same time. There may be other reasons this happens as well.
The best thing to do is to turn your device off and on, or just shut the game down and start it again.
To make sure the game has been completely shut down, it will have to reload from the beginning again and not just open at where you left off. You may also search google on how to shut the game down completely on your specific device.
Games that may be played on tablets and phone are listed on the website. See the game name and underneath you will find the games compatibility listing. Games made in Game Maker may be played on all platforms. However, some games made in Unity may best be played on PC’s & laptops. Therefore, we recommend for optimal performance, Unity Games be played on PC’s & laptops
We also advise that these games should only be played using a web browser such as Chrome, Fire Fox or Microsoft Edge. These games are not designed to be played using the Safari browsers. It is also advised you have the latest version of the Chrome, Fire Fox or Microsoft Edge web browsers.