I find this game a great means of stress-relief. This used to cost $0.99 on the App Store but now the Free version has been released (many items from the original No Mercy are included), so you can reduce stress level without paying anything!
Have a look: https://itunes.apple.com/us/app/kick-the-buddy-no-mercy-free/id648870442?mt=8&at=10l3Vy
Have a look: https://itunes.apple.com/us/app/kick-the-buddy-no-mercy-free/id648870442?mt=8&at=10l3Vy