/ip firewall filter
add action=drop chain=forward dst-address-list=Steam src-address=192.168.50.0/24 comment="Blocking Steam on RouterOS using Address-Lists"

/ip firewall address-list
add address=45.121.184.0/23 list=Steam
add address=45.121.186.0/23 list=Steam
add address=103.10.124.0/24 list=Steam
add address=103.10.125.0/24 list=Steam
add address=103.28.54.0/23 list=Steam
add address=146.66.152.0/23 list=Steam
add address=146.66.154.0/24 list=Steam
add address=146.66.155.0/24 list=Steam
add address=146.66.156.0/23 list=Steam
add address=146.66.158.0/23 list=Steam
add address=153.254.86.0/24 list=Steam
add address=155.133.224.0/23 list=Steam
add address=155.133.227.0/24 list=Steam
add address=155.133.228.0/23 list=Steam
add address=155.133.230.0/23 list=Steam
add address=155.133.232.0/24 list=Steam
add address=155.133.233.0/24 list=Steam
add address=155.133.234.0/24 list=Steam
add address=155.133.235.0/24 list=Steam
add address=155.133.236.0/23 list=Steam
add address=155.133.238.0/24 list=Steam
add address=155.133.239.0/24 list=Steam
add address=155.133.240.0/23 list=Steam
add address=155.133.242.0/23 list=Steam
add address=155.133.244.0/24 list=Steam
add address=155.133.245.0/24 list=Steam
add address=155.133.246.0/23 list=Steam
add address=155.133.248.0/24 list=Steam
add address=155.133.249.0/24 list=Steam
add address=155.133.250.0/24 list=Steam
add address=155.133.252.0/24 list=Steam
add address=155.133.253.0/24 list=Steam
add address=155.133.254.0/24 list=Steam
add address=155.133.255.0/24 list=Steam
add address=162.254.192.0/24 list=Steam
add address=162.254.193.0/24 list=Steam
add address=162.254.194.0/23 list=Steam
add address=162.254.196.0/24 list=Steam
add address=162.254.197.0/24 list=Steam
add address=162.254.198.0/24 list=Steam
add address=162.254.199.0/24 list=Steam
add address=185.25.180.0/23 list=Steam
add address=185.25.182.0/24 list=Steam
add address=185.25.183.0/24 list=Steam
add address=190.216.121.0/24 list=Steam
add address=190.217.33.0/24 list=Steam
add address=192.69.96.0/23 list=Steam
add address=205.185.194.0/24 list=Steam
add address=205.196.6.0/24 list=Steam
add address=208.64.200.0/24 list=Steam
add address=208.64.201.0/24 list=Steam
add address=208.64.202.0/24 list=Steam
add address=208.64.203.0/24 list=Steam
add address=208.78.164.0/23 list=Steam
add address=208.78.166.0/24 list=Steam
add address=208.78.167.0/24 list=Steam