Game pauses when switching browser tabs

If freezing and continuing from where the game was ruins the gameplay in some way then store the outcome and display it to the user when they return, like the game is over and here is the result.

If you really need it and dont mind using Construct 2 then it is possible by using a Plugin. I use it all the time but for personal projects that is not meant for release to the public. It is a great plugin and is a shame that it wasn't ported to C3.

I suspect that other games you've seen that appear to be running in the background are in fact using either the timer-based approach or catch-up-time approaches that Construct can also support. Any app that genuinely runs constantly in the background will do things like spin up laptop fans and drain battery, which people don't like and usually leave negative reviews for, and it's unnecessary and wasteful compared to the other approaches.

Just out of curiosity, why is it so important the game continues to run in the background, and why is it ok for the player to leave the game to go do something else and possibly forgetting the game is still running?

The game is running for multiple users at the same time, so if you switch tabs it should continue for both users. Search on Google for casino aviator and you will see what I am talking about, there are multiple users placing bets in real time and when the timer ends the game starts and the bets are closed.