contract Mortal is Ownable{
    uint public stopTS;
    uint public minimumWait = 1 hours;
    bool public killed;

    /**
     * keep people from joining games or initiating new ones
     * */
    function stopPlaying() public onlyOwner{
        stopTS = now;
    }

    /**
     * kills the contract if enough time has passed. time to pass = twice the waiting time for withdrawal of funds of a running game.
     * */
    function kill() public onlyOwner{
        require(stopTS > 0 && stopTS + 2 * minimumWait <= now, "before killing, playing needs to be stopped and sufficient time has to pass");
        selfdestruct(owner);
    }

    /**
     * like killing, because playing will no longer be possible and funds are withdrawn, but keeps the data available on the blockchain
     * (especially scores)
     * */
    function permaStop() public onlyOwner{
        require(stopTS > 0 && stopTS + 2 * minimumWait <= now, "before killing, playing needs to be stopped and sufficient time has to pass");
        killed = true;
        owner.transfer(address(this).balance);
    }

    /**
     * resume playing. stops the killing preparation.
     * */
    function resumePlaying() public onlyOwner{
        require(!killed, "killed contract cannot be reactivated");
        stopTS = 0;
    }

    /**
     * don't allow certain functions if playing has been stopped
     * */
    modifier active(){
        require(stopTS == 0, "playing has been stopped by the owner");
        _;
    }
}
function kill() public onlyOwner{
    require(stopTS > 0 && stopTS + 2 * minimumWait <= now, "before killing, playing needs to be stopped and sufficient time has to pass");
    selfdestruct(owner);
}

/**
 * kills the contract if enough time has passed. time to pass = twice the waiting time for withdrawal of funds of a running game.
 * */