If you want your kid to play outside instead in League of Legends this might help you.

You need to find the ip addresses associated with lol. This is done by visiting this url

Then you need to ban all UDP traffic here is how I have done this with iptables.

I understand that there should be much more simpler way.

if true ; then
/sbin/iptables -A INPUT  -p udp  -s 8.23.24.0/23 -j DROP
/sbin/iptables -A INPUT  -p udp  -s 104.160.128.0/19 -j DROP
/sbin/iptables -A INPUT  -p udp  -s 64.124.200.200/29 -j DROP
/sbin/iptables -A INPUT  -p udp  -s 192.207.0.0/24 -j DROP
/sbin/iptables -A INPUT  -p udp  -s 162.249.72.0/21 -j DROP
/sbin/iptables -A INPUT  -p udp  -s 192.64.168.0/21 -j DROP

/sbin/iptables -A OUTPUT  -p udp  -d 8.23.24.0/23 -j DROP
/sbin/iptables -A OUTPUT  -p udp  -d 104.160.128.0/19 -j DROP
/sbin/iptables -A OUTPUT  -p udp  -d 64.124.200.200/29 -j DROP
/sbin/iptables -A OUTPUT  -p udp  -d 192.207.0.0/24 -j DROP
/sbin/iptables -A OUTPUT  -p udp  -d 162.249.72.0/21 -j DROP
/sbin/iptables -A OUTPUT  -p udp  -d 192.64.168.0/21 -j DROP

/sbin/iptables -A FORWARD  -p udp  -s 8.23.24.0/23 -j DROP
/sbin/iptables -A FORWARD  -p udp  -s 104.160.128.0/19 -j DROP
/sbin/iptables -A FORWARD  -p udp  -s 64.124.200.200/29 -j DROP
/sbin/iptables -A FORWARD  -p udp  -s 192.207.0.0/24 -j DROP
/sbin/iptables -A FORWARD  -p udp  -s 162.249.72.0/21 -j DROP
/sbin/iptables -A FORWARD  -p udp  -s 192.64.168.0/21 -j DROP

/sbin/iptables -A FORWARD  -p udp  -d 8.23.24.0/23 -j DROP
/sbin/iptables -A FORWARD  -p udp  -d 104.160.128.0/19 -j DROP
/sbin/iptables -A FORWARD  -p udp  -d 64.124.200.200/29 -j DROP
/sbin/iptables -A FORWARD  -p udp  -d 192.207.0.0/24 -j DROP
/sbin/iptables -A FORWARD  -p udp  -d 162.249.72.0/21 -j DROP
/sbin/iptables -A FORWARD  -p udp  -d 192.64.168.0/21 -j DROP
fi

here is how I block the website of the “great” game.

/sbin/iptables -A INPUT -d 95.172.69.0/24 -j DROP
/sbin/iptables -A INPUT -d 74.201.71.0/24 -j DROP
/sbin/iptables -A INPUT -d 66.151.54.0/24 -j DROP