Shell script to kill custom apps, run another app then restart killed apps?
You can use an Tasker to kill apps when you launch your game. And you are also able to do the opposite, when your game gets closed, Tasker can initialize other apps.
You may use the trial version to test this, but I believe that better results can only be achieved with root.

Tasker
Tasker by Crafty Apps available from Google Play Store (4,49€)
From their website you have a free 14-day trial download.